THERMAL RADIATION (THERM)

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "THERMAL RADIATION (THERM)"

Transcription

1 UNIVERSITY OF SURREY DEPARTMENT OF PHYSICS Level 2 Classical Laboratory Experiment THERMAL RADIATION (THERM) Objectives In this experiment you will explore the basic characteristics of thermal radiation, particularly emission, reflection and transmission. You will test the inverse square law of thermal radiation. Additionally, you will verify the Stefan-Boltzmann law for a black body at high and low temperatures. Background: Thermal energy is transferred from one place to another by three processes: convection, conduction or radiation. In convection, matter moves away from a region and carries heat with it. A common example is the heating (or cooling) of an object by the movement of surrounding air. In conduction, the atoms or molecules making up a substance interact in order to transport hear. An example is the vibration of atoms in a crystal lattice transporting heat along a metal rod. (Heat conduction is studied in another second year laboratory experiment.) In this exercise, you will be focussing on the third of these mechanisms, thermal radiation in the form of electromagnetic waves. Thermal radiation of objects near room temperature (and also near the temperature of the human body) is mainly in the infrared region of the electromagnetic spectrum. At higher temperatures - about 600 or 700 C - radiation will start to be in the visible region. Thus, an object glows red or orange at such temperatures. At even higher temperatures, emission of light will be throughout the visible region and the object might be described as white hot. The wavelength of radiation at which the power is a maximum, λ, varies as the reciprocal of absolute temperature, T. Wien s law states that λ = b/t where b is a constant equal to mm.k. The amount of thermal radiation given off by an object obviously varies with its temperature. In 1879 Josef Stefan found an empirical relationship between the absolute temperature of an object, T, and the thermal power (P) per unit area (A) radiated by an object, denoted by R: 1 of 10

2 R = P/A = eσt 4 where e is called the emissivity, and the constant of proportionality, σ, is equal to x 10-8 Wm -2 K -4. Emissivities vary between 0 and 1. Ludwig Boltzmann derived this equation theoretically in the 1880s, and so it is now referred to as the Stefan-Boltzmann law. An ideal black body perfectly absorbs all radiation that strikes it and is also a perfect emitter and has e = 1. When radiation falls on an object, a portion of the radiation is reflected and the remainder is absorbed. Dark objects absorb more radiation than light objects and so usually have higher emissivities. Lighter objects are better reflectors. Just as the Stefan-Boltzmann law describes how radiation emission varies with temperature, the radiation absorbed, Rabs, can be described by: Rabs = P/A = aσt 4, where a is the coefficient of absorption and, like the emissivity, varies between 0 and 1. When a hot object is in surroundings at a lower temperature, it emits more radiation than it absorbs. When the object is in thermal equilibrium with its surroundings, then the rate of emission and absorption of radiation must be the same, and so e = a. The net power per unit area radiated by an object at a temperature T in a room at a temperature To is then R = eσ(t 4 - To 4 ). You will attempt to verify the Stefan-Boltzmann law in the laboratory. At very high temperatures, the amount of radiation absorbed is negligible compared to that emitted, and so it can be neglected. Overview of the Experiments: Over the two weeks of this experiment, you will perform a series of four experiments to study: Thermal Emission, Reflection and Transmission Stefan-Boltzman Law at Low Temperatures Inverse Square Law Stefan-Boltzman Law at High Temperatures and to do this you have the following equipment: a radiation cube (known as a Leslie s cube) a lamp with a tungsten filament a radiation sensor. The cube is simply an aluminium box containing a 100 W light bulb. The temperature of the four vertical faces of the cube can be varied up to a maximum of about 150 C by varying the power to the light bulb. A thermistor ( measuring temperature-dependent resistance) allows the 2 of 10

3 determination of the cube temperature. Each face of the cube has a different treatment: black paint, white paint, smooth polish, and rough texture. Using the lamp, you can generate temperatures of up to 3000 C in the filament by varying the current. The electrical resistance of the filament varies with temperature, which enables its temperature to be tracked as the current is changed. The radiation sensor contains a miniature thermopile, constructed from thermocouples, that produces a voltage proportional to the incoming radiation intensity in its region of sensitivity, namely the infrared region from about 0.5 to 40 µm in wavelength. Week 1 Thermal Emission and Transmission First, you will study how different surfaces compare in terms of the amount of radiation they emit when they are at the same temperature. Then, you will observe how different materials transmit thermal radiation, and finally you will measure quantitatively how the radiated power varies with temperature. These measurements will all use the Leslie s Cube apparatus. 1.1 Emission and transmission for different surfaces: 1. You need to connect the two digital multimeters (DMMs) to the two devices used for these experiments, namely: to the Radiation Cube (to read the resistance of its thermistor) to the radiation sensor (to read its output voltage) 2. Measure the resistance in ohms of the thermistor in the cube. This will be your reference measurement at room temperature. 3. As soon as possible, after you have measured its resistance, switch on the power to the Leslie cube, to get it heating up to the required temperature. You need it to equilibrate at a setting of about 5, to get good results. You can gain time in the heating by initially setting the power to high, for a few minutes. (The panel of the Leslie s cube is shown below:) 4. While the cube is heating, set up the sensor so that you will be ready to make the measurements described in item (7) below. Also, work out how to compute the temperature of the cube from the measured resistance of the thermistor as discussed in (6) below. 5. Allow the cube to reach thermal equilibrium at a setting of about 5. 3 of 10

4 6. Values of resistance from the temperature sensor (thermistor) in the cube correspond to the temperature values shown in the table on the side of the cube. These values have been put into a spreadsheet that is available for download at called leslies-cube.xls, and this includes code for linear interpolation between the data points. (Alternatively, typing cd drhosea heateng at the C:\ prompt will run a program on the PC near the experiment that also does a linear interpolation, or you can write your own code to do the interpolation). 6. Measure the resistance of the thermistor in the equilibrated cube, so that you can calculate its temperature. 7. Use the sensor to measure the radiation from one of the vertical faces of the cube. To ensure that the sensor is held at a fixed distance from the cube surface for each measurement, place the sensor so that the posts on its end are in contact with the surface. For the measurement, press to open the cover on the sensor, note the reading on the DMM, and release to close the cover again. This procedure prevents the sensor itself from being heated up. The reading will be measured in mv. 8. Repeat for each surface, recording the sensor reading in mv, the thermistor resistance, and the corresponding temperature of the cube. 9. Turn the power setting on the cube to HIGH and wait for the cube to reach equilibrium. 10. Measure the four faces of the cube again to measure the radiation emitted from each surface, at the higher temperature. Analysis: construct a table showing how emissivity varies with temperature and with the type of cube surface. Normalise your relative measurements of the emissivity to a value of unity for the black surface (as your closest approximation to an ideal blackbody) in order to be able to quote absolute values and compare with published data. Do all surfaces at a given temperature emit the same amount of radiation? Explain your findings. 1.2 Transmission: 1. With the cube is at its highest temperature, as at the end of the previous measurements, place the sensor (on its stand, with its shield covering it) at a distance of about 4 cm from the black surface. 2. Open the shield and quickly record the sensor reading, and then close the shield. 3. Next place a sheet of glass between the sensor and the cube. 4. Quickly open the shield, take a reading, and close the shield again. 5. Repeat with the glass removed, to ensure reproducibility with no absorber. 6. Repeat this procedure with a piece of paper and with the black cloth and the space blanket material provided. Analysis: how does the transmission of radiation through glass, paper and cloth etc. compare? From your findings, explain how a greenhouse functions. 4 of 10

5 Question: calculate how much net energy a person will radiate in a room at 20 C. Note that skin temperature is usually about 33 C, and assume that the surface area of the person is 1.4 square metres. Discuss your findings. 1.3 Stefan-Boltzmann Law at Low Temperatures: 1. Maintain the setup from the end of the previous measurement, i.e. with the cube is at its highest temperature and the sensor (on its stand, with its shield covering it) at a distance of about 4 cm from the black surface. 2. Make a sensor reading to record the radiation level, then close the shield. Also, measure the resistance of the thermistor, to give the temperature of the cube. 3. You should aim to make as many additional measurements as you can, going down in temperature in steps of about 15 C, without disturbing the setup of the sensor relative to the cube. You can use your earlier measured temperature, for a cube power setting of 5, to get an idea of what adjustment to make to the cube power between measurements. 4. At each temperature, check that the cube s temperature has stabilised sufficiently to make the measurement, by monitoring the thermistor resistance. Take the readings of the sensor output and the thermistor resistance at the same, as closely as possible. 5. During your measurements, take the opportunity to use your measured resistance of the thermistor at room temperature to deduce the value of the room temperature according to the thermistor (needed in the analysis). Analysis: you will need to take into account the fact that the radiation sensor is itself radiating thermal energy (according to the Stefan-Boltzmann law). The voltage reading of the radiation sensor is proportional to the amount of radiation striking it minus the radiation being emitted. Mathematically, we can write that the radiation sensor voltage, V, will vary as: V ~ σ(t 4 - T det 4 ) where T is the absolute temperature of the radiation source and T det is the temperature of the detector (room temperature). You have thermistor measurements to give you each of these temperatures. Plot V against (T 4 - T det 4) and comment on how your data compare to the expected straight line. What is the y-intercept? Interpret your results in terms of the Stefan- Boltzmann law. 5 of 10

6 Week 2 Thermal Emission and Reflection/Absorption You will mainly use the lamp and the radiation sensor for these measurements, but you need the Leslie s Cube at room temperature for the first set of measurements. The lamp is used as a high temperature thermal point source. You will measure the fall-off of radiation flux with distance, and the variation with temperature of the amount of power radiated in a higher temperature regime than could be accessed with the Leslie s cube. For the measurements to examine the Stefan-Boltzmann Law, you will need to know the resistance of the lamp filament at room temperature very accurately, and that will be the first measurement (before the lamp heats up). 2.1 Experiment to examine the Inverse Square Law The inverse square law states that the radiation flux from a point source varies as one over the square of the distance from the source. You will measure the thermal radiation at various distances from the lamp to test this law. 1. With a sensitive DMM and banana plugs, measure the resistance of the lamp filament at ROOM TEMPERATURE. Accuracy is important. Read the resistance to as many digits as possible. Also find out and note the measured room temperature. 2. Connect the lamp to the power supply, but keep it switched OFF. 3. Connect a DMM to the thermopile radiation sensor. 4. Tape a metre rule to the bench top, such that the lamp is at one end of the metre stick with the centre of its filament is exactly over the zero-point of the rule. 5. Attach the sensor to the stand and adjust its height so that it is exactly the same height as the lamp s filament. 6. Align the axes of the lamp and the sensor with that of the metre rule. 7. With the lamp OFF, record the ambient radiation level in the room at four or five distances along the meter stick. Determine the average value. 8. Turn on the power supply to the lamp, and set the voltage to about 10 V. 9. If the sensor heats up, the readings would be affected. Therefore shield the sensor between readings with the reflective heat shield. 10. Record the radiation sensor readings at distances between 2.5 cm and 80 cm from the lamp. Recommended distances are: from 2.5 cm to 5.0 cm in steps of 0.5 cm; then in steps of 1 cm up to 10 cm; then 20 cm to 80 cm in steps of 20 cm. (This gives 15 data points; discuss why the spread of values is reasonable for the particular measurement being made). 11. Keep the lamp on, and the sensor set up for the following experiments. Analysis: subtract the ambient radiation level from your readings of the lamp s radiation. Plot the radiation level (in mv) against the inverse square of the distance between the sensor and the lamp filament. Do your data fall on a straight line? For a power law y x α as exemplified here by the inverse square law, a plot on a log-log graph is useful, since y = c x α means that ln y = α (ln x) + c (where c = ln c) 6 of 10

7 and the result is a straight line with a slope equal to α (in this case, 2). Comment on your results. What are sources of error in your experiment? Is the lamp a good approximation to a point source? How could you improve your measurements or your analysis? 2.2 Reflection of thermal radiation This should be a quick few measurements that you can make between the Inverse Square experiment and the final part, where you will measure the Stefan-Boltzmann variation of power with temperature, at high temperatures. You will collect results for reflection (i.e. a measure of absorption) that you can compare with the Week 1 results for emission from the Leslie cube surfaces. 1. Keep the experimental setup from the previous experiment to examine the Inverse Square law (but there is no further need for the metre rule). 2. You will use the lamp to direct thermal radiation at the surfaces of the Leslie s cube, and the sensor to record the reflected radiation. The cube does not need to be connected to the power because you will leave it unpowered, at room temperature. Take the sensor on its stand and point it at about a 45 angle to the polished surface of the cube. The distance from the sensor to the cube should be less than about 10 cm. The shield on the sensor should be covering the sensor. 3. The lamp should still be set at about 10 V from the previous experiment now, increase the voltage to about 11.5 volts. DO NOT EXCEED 12 V. 4. Position the lamp filament at a 45 degree angle to the cube surface, so as to allow radiation from the lamp to be reflected to the sensor. 5. Wait for the temperature of the filament to stabilise so that you can compare the measurements you will make with different surfaces. 6. When the temperature of the lamp Remove the shield from the sensor and quickly record the sensor reading. 7. Repeat this experiment under identical conditions for the three other surfaces of the cube, and finally repeat the polished surface to check for consistency. Keep the lamp powered on for the next experiment. Analysis: construct a table showing how reflectivity varies with the type of cube surface. Normalise your relative measurements of the reflectivity to a value of unity for the polished surface (as your closest approximation to an ideal reflector) in order to be able to quote absolute values and compare with your data for emissivity. Explain how and why emissivity and reflectivity are related. 2.3 Stefan-Boltzman Law at High Temperatures You will measure the thermal radiation from the lamp at varying high temperatures to examine the Stefan-Boltzmann law. In order to determine the temperature of the lamp, you will measure the electrical resistance of its filament. As its temperature increases, so does its resistance. You require just the lamp and the sensor and the two DMMs for this measurement. 7 of 10

8 1. Make a note of the measurement of the resistance of the lamp filament at ROOM TEMPERATURE that you made at the beginning of Keep the lamp set up and powered to about 11.5 V as in the previous experiment. 3. The thermopile radiation sensor should already be connected to its DMM and mounted on its stand. Position its end to a distance of 6 cm from the lamp filament. 4. Check that the height of the sensor is at the same level as the filament. 5. Make your first measurement: record the radiation flux at this temperature of the filament. Try to make the measurement quickly (open the shutter for a short time) so as not to heat up the sensor. 6. Measure the resistance of the lamp filament at the present temperature by using the DMM to measure voltageand also noting down the current from the power supply. You can convert the deduced resistance to a measurement of the filament temperature using your room temperature measurement and the data for tungsten included in Annex I. Details are given below. You can also use the measured current and resistance (or voltage) to calculate the power input into the lamp. 7. You should record the radiation flux for a range of temperature values of the filament, coming down from the maximum at which you began. Choose temperature values according to the time available and knowing that you plan to verify the Stefan-Boltzmann equation. At each temperature, record the values of the radiation flux, the filament resistance and the current from the power supply while the temperature is sufficiently steady at a constant value during the measurements. 8. It is by comparing the results from different temperatures that you can verify the Stefan-Boltzmann equation, so it is important to measure for several temperatures. Temperature of the filament: The thermistor calibration data in Annex I use the ratio of the resistance at temperature T to the resistance at 300K, in order to deduce the value of T. You have a reference measurement at room temperature, but you need to convert it to a reference measurement at 300K in order to use the thermistor data accurately. By linear interpolation using the data in Annex I, you can deduce the ratio between the room temperature resistance and the resistance at 300K, and compute the latter quantity (equivalent to a correction of up to a few percent). The tabulated values in Annex I have been put into a spreadsheet called tungsten-resistivity.xls and downloadable from The spreadsheet includes some code for calculating this correction to your measured room temperature resistance. With your computed 300K resistance, you are then ready to calculate temperature by using the resistance R(T) measured at temperature T, expressed as the ratio R(T)/R(300K). The instructions for using either a fit to the data, or a quadratic interpolation procedure, to convert any measured ratio of resistance into temperature are given in the spreadsheet, or you can calculate the interpolations without the spreadsheet. 8 of 10

9 Analysis: 1. Prepare a log-log plot of radiation (measured in mv) against absolute temperature (K). (See discussion of log-log plots under 2.1). Perform a linear regression analysis on your data to determine the power of the dependence. 2. Does radiation vary with the fourth power of temperature? Does the dependence hold better at higher or lower temperatures? What are the main sources of error?is it valid to ignore the background at these higher temperatures (compared to experiment 1.3)? The glass in the lamp absorbs some infrared radiation. Do you think this has a significant effect? 3. Is the lamp filament a black body? 4. Use the Stefan-Boltzmann law to calculate the power of thermal radiation per unit area, R, in W/m 2 produced by the lamp filament at a few different temperatures. (You will need to estimate a value for the emissivity.) How does this value compare to the energy input into the lamp (equal to IV) divided by the surface area of the filament? (You will need to estimate the surface area of the filament.) Comment on the values obtained. This script is an update of the experiment developed by J.L. Keddie and is adapted from the script by MS and JLK dated 22 October W.N. Catford, September (end) 9 of 10

10 These data are also available electronically in the file tungsten-resistivity.xls at 10 of 10

Blackbody Radiation References INTRODUCTION

Blackbody Radiation References INTRODUCTION Blackbody Radiation References 1) R.A. Serway, R.J. Beichner: Physics for Scientists and Engineers with Modern Physics, 5 th Edition, Vol. 2, Ch.40, Saunders College Publishing (A Division of Harcourt

More information

Principle of Thermal Imaging

Principle of Thermal Imaging Section 8 All materials, which are above 0 degrees Kelvin (-273 degrees C), emit infrared energy. The infrared energy emitted from the measured object is converted into an electrical signal by the imaging

More information

Heat Transfer: Radiation

Heat Transfer: Radiation Heat Transfer: Radiation Heat transfer occurs by three mechanisms: conduction, convection, and radiation. We have discussed conduction in the past two lessons. In this lesson, we will discuss radiation.

More information

Energy Transport. Focus on heat transfer. Heat Transfer Mechanisms: Conduction Radiation Convection (mass movement of fluids)

Energy Transport. Focus on heat transfer. Heat Transfer Mechanisms: Conduction Radiation Convection (mass movement of fluids) Energy Transport Focus on heat transfer Heat Transfer Mechanisms: Conduction Radiation Convection (mass movement of fluids) Conduction Conduction heat transfer occurs only when there is physical contact

More information

How Matter Emits Light: 1. the Blackbody Radiation

How Matter Emits Light: 1. the Blackbody Radiation How Matter Emits Light: 1. the Blackbody Radiation Announcements n Quiz # 3 will take place on Thursday, October 20 th ; more infos in the link `quizzes of the website: Please, remember to bring a pencil.

More information

Take away concepts. What is Energy? Solar Energy. EM Radiation. Properties of waves. Solar Radiation Emission and Absorption

Take away concepts. What is Energy? Solar Energy. EM Radiation. Properties of waves. Solar Radiation Emission and Absorption Take away concepts Solar Radiation Emission and Absorption 1. 2. 3. 4. 5. 6. Conservation of energy. Black body radiation principle Emission wavelength and temperature (Wein s Law). Radiation vs. distance

More information

EXPERIMENT 6 PHYSICS 250 THERMAL MEASUREMENTS

EXPERIMENT 6 PHYSICS 250 THERMAL MEASUREMENTS EXPERIMENT 6 PHYSICS 250 THERMAL MEASUREMENTS Apparatus: Electronic multimeter Iron-constantan thermocouple Thermistor Hot plate Electronic thermometer with two leads Glass beaker Crushed ice Methyl alcohol

More information

- the total energy of the system is found by summing up (integrating) over all particles n(ε) at different energies ε

- the total energy of the system is found by summing up (integrating) over all particles n(ε) at different energies ε Average Particle Energy in an Ideal Gas - the total energy of the system is found by summing up (integrating) over all particles n(ε) at different energies ε - with the integral - we find - note: - the

More information

EM Radiation and the Greenhouse Effect

EM Radiation and the Greenhouse Effect EM Radiation and the Greenhouse Effect As you are no-doubt aware, the greenhouse effect has become a major global issue. As usual, we will try to keep our attention on the physics. What is the greenhouse

More information

The Nature of Electromagnetic Radiation

The Nature of Electromagnetic Radiation II The Nature of Electromagnetic Radiation The Sun s energy has traveled across space as electromagnetic radiation, and that is the form in which it arrives on Earth. It is this radiation that determines

More information

UNIT 1 GCSE PHYSICS 1.1.1 Infrared Radiation 2011 FXA

UNIT 1 GCSE PHYSICS 1.1.1 Infrared Radiation 2011 FXA 1 All objects emit and absorb thermal radiation. The hotter an object is the infrared radiation it radiates in a given time. It is continually being transferred to and from all objects. The hotter the

More information

Is a Back Radiation Greenhouse Effect of 33 Kelvin Possible? Ross McLeod, Assoc. Diploma Health Surveying, B. Tech. (Engineering) May

Is a Back Radiation Greenhouse Effect of 33 Kelvin Possible? Ross McLeod, Assoc. Diploma Health Surveying, B. Tech. (Engineering) May Is a Back Radiation Greenhouse Effect of 33 Kelvin Possible? Ross McLeod, Assoc. Diploma Health Surveying, B. Tech. (Engineering) May 29 2013 Updated August 7 2013 ABSTRACT This paper seeks to demonstrate

More information

The Experimental Basis of Quantum Theory

The Experimental Basis of Quantum Theory The Experimental Basis of Quantum Theory Preliminary Remarks New theories do not appear from nowhere, they are usually based on (unexplained) experimental results. People have to be ready for it, e.g.

More information

Is a Back Radiation Greenhouse Effect of 33 Kelvin Possible?

Is a Back Radiation Greenhouse Effect of 33 Kelvin Possible? Is a Back Radiation Greenhouse Effect of 33 Kelvin Possible? by Ross McLeod, Assoc.Dip.Health Surveying B.Tech. (Eng.) updated version March 1, 2014 This is a PROM* Paper and subject to ongoing review

More information

Resistance, Ohm s Law, and the Temperature of a Light Bulb Filament

Resistance, Ohm s Law, and the Temperature of a Light Bulb Filament Resistance, Ohm s Law, and the Temperature of a Light Bulb Filament Name Partner Date Introduction Carbon resistors are the kind typically used in wiring circuits. They are made from a small cylinder of

More information

Solar Energy. Outline. Solar radiation. What is light?-- Electromagnetic Radiation. Light - Electromagnetic wave spectrum. Electromagnetic Radiation

Solar Energy. Outline. Solar radiation. What is light?-- Electromagnetic Radiation. Light - Electromagnetic wave spectrum. Electromagnetic Radiation Outline MAE 493R/593V- Renewable Energy Devices Solar Energy Electromagnetic wave Solar spectrum Solar global radiation Solar thermal energy Solar thermal collectors Solar thermal power plants Photovoltaics

More information

Laboratory 15: Spectroscopy

Laboratory 15: Spectroscopy Spectroscopy 1 aboratory 15: Spectroscopy A transmission diffraction grating consists of a large number of closely spaced parallel lines ruled on some transparent material such as glass. The ruled lines

More information

Carbon Cable. Sergio Rubio Carles Paul Albert Monte

Carbon Cable. Sergio Rubio Carles Paul Albert Monte Carbon Cable Sergio Rubio Carles Paul Albert Monte Carbon, Copper and Manganine PhYsical PropERTieS CARBON PROPERTIES Carbon physical Properties Temperature Coefficient α -0,0005 ºC-1 Density D 2260 kg/m3

More information

The Electrical Properties of Materials: Resistivity

The Electrical Properties of Materials: Resistivity The Electrical Properties of Materials: Resistivity 1 Objectives 1. To understand the properties of resistance and resistivity in conductors, 2. To measure the resistivity and temperature coefficient of

More information

Electrical Equivalent of Heat Apparatus

Electrical Equivalent of Heat Apparatus Name Class Date Electrical Equivalent of Heat Equipment Needed Temperature Sensor Current Sensor Voltage Sensor Electrical Equivalent of Heat Apparatus Balance Digital Multimeter Low Voltage Power Supply

More information

Lab E1: Introduction to Circuits

Lab E1: Introduction to Circuits E1.1 Lab E1: Introduction to Circuits The purpose of the this lab is to introduce you to some basic instrumentation used in electrical circuits. You will learn to use a DC power supply, a digital multimeter

More information

PHYS-2212 LAB Ohm s Law and Measurement of Resistance

PHYS-2212 LAB Ohm s Law and Measurement of Resistance Objectives PHYS-2212 LAB Ohm s Law and Measurement of Resistance Part I: Comparing the relationship between electric current and potential difference (voltage) across an ohmic resistor with the voltage-current

More information

Mechanisms of Heat Transfer. Amin Sabzevari

Mechanisms of Heat Transfer. Amin Sabzevari Mechanisms of Heat Transfer Amin Sabzevari Outline Definition of Heat and Temperature Conduction, Convection, Radiation Demonstrations and Examples What is Heat? Heat is the spontaneous flow of energy

More information

Lecture 2: Radiation/Heat in the atmosphere

Lecture 2: Radiation/Heat in the atmosphere Lecture 2: Radiation/Heat in the atmosphere TEMPERATURE is a measure of the internal heat energy of a substance. The molecules that make up all matter are in constant motion. By internal heat energy, we

More information

Chapter 2: Solar Radiation and Seasons

Chapter 2: Solar Radiation and Seasons Chapter 2: Solar Radiation and Seasons Spectrum of Radiation Intensity and Peak Wavelength of Radiation Solar (shortwave) Radiation Terrestrial (longwave) Radiations How to Change Air Temperature? Add

More information

University of California at Santa Cruz Electrical Engineering Department EE-145L: Properties of Materials Laboratory

University of California at Santa Cruz Electrical Engineering Department EE-145L: Properties of Materials Laboratory University of California at Santa Cruz Electrical Engineering Department EE-145L: Properties of Materials Laboratory Lab 8: Optical Absorption Spring 2002 Yan Zhang and Ali Shakouri, 05/22/2002 (Based

More information

The Greenhouse Effect

The Greenhouse Effect The Greenhouse Effect THE GREENHOUSE EFFECT To understand the greenhouse effect you first need to know a bit about solar radiation what it is, where it comes from and what happens when it reaches Earth.

More information

Radiation Transfer in Environmental Science

Radiation Transfer in Environmental Science Radiation Transfer in Environmental Science with emphasis on aquatic and vegetation canopy media Autumn 2008 Prof. Emmanuel Boss, Dr. Eyal Rotenberg Introduction Radiation in Environmental sciences Most

More information

Every mathematician knows it is impossible to understand an elementary course in thermodynamics. ~V.I. Arnold

Every mathematician knows it is impossible to understand an elementary course in thermodynamics. ~V.I. Arnold Every mathematician knows it is impossible to understand an elementary course in thermodynamics. ~V.I. Arnold Radiation Radiation: Heat energy transmitted by electromagnetic waves Q t = εσat 4 emissivity

More information

1(a) Name the charge carriers responsible for electric current in a metal and in an electrolyte.

1(a) Name the charge carriers responsible for electric current in a metal and in an electrolyte. Physics A Unit: G482: Electrons, Waves and Photons 1(a) Name the charge carriers responsible for electric current in a metal and in an electrolyte. Electrons are the charged particles in a metal. Cations

More information

The Three Heat Transfer Modes in Reflow Soldering

The Three Heat Transfer Modes in Reflow Soldering Section 5: Reflow Oven Heat Transfer The Three Heat Transfer Modes in Reflow Soldering There are three different heating modes involved with most SMT reflow processes: conduction, convection, and infrared

More information

Physics 221 Lab 14 Transformers & Atomic Spectra

Physics 221 Lab 14 Transformers & Atomic Spectra Physics 221 Lab 14 Transformers & Atomic Spectra Transformers An application of Inductance The point of a transformer is to increase or decrease the voltage. We will investigate a simple transformer consisting

More information

ESCI 107/109 The Atmosphere Lesson 2 Solar and Terrestrial Radiation

ESCI 107/109 The Atmosphere Lesson 2 Solar and Terrestrial Radiation ESCI 107/109 The Atmosphere Lesson 2 Solar and Terrestrial Radiation Reading: Meteorology Today, Chapters 2 and 3 EARTH-SUN GEOMETRY The Earth has an elliptical orbit around the sun The average Earth-Sun

More information

Energy Pathways in Earth s Atmosphere

Energy Pathways in Earth s Atmosphere BRSP - 10 Page 1 Solar radiation reaching Earth s atmosphere includes a wide spectrum of wavelengths. In addition to visible light there is radiation of higher energy and shorter wavelength called ultraviolet

More information

Chemistry 111 Lab: Intro to Spectrophotometry Page E-1

Chemistry 111 Lab: Intro to Spectrophotometry Page E-1 Chemistry 111 Lab: Intro to Spectrophotometry Page E-1 SPECTROPHOTOMETRY Absorption Measurements & their Application to Quantitative Analysis study of the interaction of light (or other electromagnetic

More information

Characteristic curves of a solar cell

Characteristic curves of a solar cell Related topics Semi-conductor, p-n junction, energy-band diagram, Fermi characteristic energy level, diffusion potential, internal resistance, efficiency, photo-conductive effect, acceptors, donors, valence

More information

IDEAL AND NON-IDEAL GASES

IDEAL AND NON-IDEAL GASES 2/2016 ideal gas 1/8 IDEAL AND NON-IDEAL GASES PURPOSE: To measure how the pressure of a low-density gas varies with temperature, to determine the absolute zero of temperature by making a linear fit to

More information

Atomic Emission Spectra

Atomic Emission Spectra Atomic Emission Spectra Objectives The objectives of this laboratory are as follows: To build and calibrate a simple box spectroscope capable of measuring wavelengths of visible light. To use this spectroscope

More information

PHYS245 Lab: Light bulb and resistor ΙΙ: Current voltage (I-V) curves

PHYS245 Lab: Light bulb and resistor ΙΙ: Current voltage (I-V) curves Purpose: PHYS245 Lab: Light bulb and resistor ΙΙ: Current voltage (I-V) curves Measure the current voltage curve of a light bulb and a resistor using a variable d.c. power supply. Understanding of Ohm

More information

Overview. What is EMR? Electromagnetic Radiation (EMR) LA502 Special Studies Remote Sensing

Overview. What is EMR? Electromagnetic Radiation (EMR) LA502 Special Studies Remote Sensing LA502 Special Studies Remote Sensing Electromagnetic Radiation (EMR) Dr. Ragab Khalil Department of Landscape Architecture Faculty of Environmental Design King AbdulAziz University Room 103 Overview What

More information

Earth s Energy Balance & the Greenhouse Effect

Earth s Energy Balance & the Greenhouse Effect Earth s Energy Balance & the Greenhouse Effect Outline: The Earth s Energy Balance: Electromagnetic Spectrum: Ultraviolet (UV) Visible Infrared (IR) Blackbody Radiation Albedo (reflectivity) Greenhouse

More information

Characteristic curves of a solar cell

Characteristic curves of a solar cell Related Topics Semi-conductor, p-n junction, energy-band diagram, Fermi characteristic energy level, diffusion potential, internal resistance, efficiency, photo-conductive effect, acceptors, donors, valence

More information

Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium

Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium Chemistry 111 Laboratory Experiment 7: Determination of Reaction Stoichiometry and Chemical Equilibrium Introduction The word equilibrium suggests balance or stability. The fact that a chemical reaction

More information

TOPIC 5 (cont.) RADIATION LAWS - Part 2

TOPIC 5 (cont.) RADIATION LAWS - Part 2 TOPIC 5 (cont.) RADIATION LAWS - Part 2 Quick review ELECTROMAGNETIC SPECTRUM Our focus in this class is on: UV VIS lr = micrometers (aka microns) = nanometers (also commonly used) Q1. The first thing

More information

Comparison of Infrared and Visible Light Absorption Properties of Water and its Application in Filtering Heat Energy from Solar Radiation

Comparison of Infrared and Visible Light Absorption Properties of Water and its Application in Filtering Heat Energy from Solar Radiation Comparison of Infrared and Visible Light Absorption Properties of Water and its Application in Filtering Heat Energy from Solar Radiation Tiasha Joardar 5124 Water Haven Lane Plano, TX 75093 2011-2012

More information

Chapter 16 Heat Transfer. Topics: Conduction Convection Radiation Greenhouse Effect/Global Warming

Chapter 16 Heat Transfer. Topics: Conduction Convection Radiation Greenhouse Effect/Global Warming Chapter 16 Heat Transfer Topics: Conduction Convection Radiation Greenhouse Effect/Global Warming Radiation Every object at a temperature above absolute zero is an emitted of electromagnetic radiation

More information

PHYSICS 1040L LAB LAB 1: INVERSE SQUARE LAW LAB

PHYSICS 1040L LAB LAB 1: INVERSE SQUARE LAW LAB PHYSICS 1040L LAB LAB 1: INVERSE SQUARE LAW LAB Objective: The student will verify the inverse square relationship between the distance and intensity of radiation. Pre-lab Questions: 1. Write a general

More information

Coal. Conversion of Solar Energy into Electrical and Thermal Energy. Introduction

Coal. Conversion of Solar Energy into Electrical and Thermal Energy. Introduction Conversion of Solar Energy into Electrical and Thermal Energy Perry LI and Moe MOMAYEZ NSF GK 12 Project Faculty Advisors for Solar Energy College of Engineering, University of Arizona Introduction Energy

More information

Preview of Period 13: Electrical Resistance and Joule Heating

Preview of Period 13: Electrical Resistance and Joule Heating Preview of Period 13: Electrical Resistance and Joule Heating 13.1 Electrical Resistance of a Wire What does the resistance of a wire depend upon? 13.2 Resistance and Joule Heating What effect does resistance

More information

Dynamic Temperature Measurements OBJECTIVES

Dynamic Temperature Measurements OBJECTIVES Dynamic Temperature Measurements OBJECTIVES (1) Investigate the dynamic response of a thermometer and a thermocouple. (2) Apply data acquisition and control to a dynamic experiment. (3) Gain experience

More information

8.3. Resistance and Ohm s Law. Did You Know? Resistance and the Flow of Electrons. Words to Know

8.3. Resistance and Ohm s Law. Did You Know? Resistance and the Flow of Electrons. Words to Know 8.3 Resistance and Ohm s Law Resistance slows down the flow of electrons and transforms electrical energy. Resistance is measured in ohms ( ). We calculate resistance by applying a voltage and measuring

More information

Upon completion of this lab, the student will be able to:

Upon completion of this lab, the student will be able to: 1 Learning Outcomes EXPERIMENT B4: CHEMICAL EQUILIBRIUM Upon completion of this lab, the student will be able to: 1) Analyze the absorbance spectrum of a sample. 2) Calculate the equilibrium constant for

More information

Energy. Mechanical Energy

Energy. Mechanical Energy Principles of Imaging Science I (RAD119) Electromagnetic Radiation Energy Definition of energy Ability to do work Physicist s definition of work Work = force x distance Force acting upon object over distance

More information

Fall 2004 Ali Shakouri

Fall 2004 Ali Shakouri University of California at Santa Cruz Jack Baskin School of Engineering Electrical Engineering Department EE-145L: Properties of Materials Laboratory Lab 5b: Temperature Dependence of Semiconductor Conductivity

More information

1. At which temperature would a source radiate the least amount of electromagnetic energy? 1) 273 K 3) 32 K 2) 212 K 4) 5 K

1. At which temperature would a source radiate the least amount of electromagnetic energy? 1) 273 K 3) 32 K 2) 212 K 4) 5 K 1. At which temperature would a source radiate the least amount of electromagnetic energy? 1) 273 K 3) 32 K 2) 212 K 4) 5 K 2. How does the amount of heat energy reflected by a smooth, dark-colored concrete

More information

VISIBLE SPECTROSCOPY

VISIBLE SPECTROSCOPY VISIBLE SPECTROSCOPY Visible spectroscopy is the study of the interaction of radiation from the visible part (λ = 380-720 nm) of the electromagnetic spectrum with a chemical species. Quantifying the interaction

More information

Cambridge International Examinations Cambridge International General Certificate of Secondary Education

Cambridge International Examinations Cambridge International General Certificate of Secondary Education Cambridge International Examinations Cambridge International General Certificate of Secondary Education *0123456789* PHYSICS 0625/04 Paper 4 Theory (Extended) For Examination from 2016 SPECIMEN PAPER 1

More information

2 1. INTENDED LEARNING OUTCOMES The students will be able to: Use physics ideas about light to explain how different types of light bulb function Desi

2 1. INTENDED LEARNING OUTCOMES The students will be able to: Use physics ideas about light to explain how different types of light bulb function Desi SCHOOLGEN ACTIVITIES Teacher-led Activity In this activity, students have the opportunity to find out why compact fluorescent ( energy efficient ) light bulbs are more efficient than conventional incandescent

More information

Unit: KPH0/4PH0 Science (Double Award) KSC0/4SC0 Paper: 1P

Unit: KPH0/4PH0 Science (Double Award) KSC0/4SC0 Paper: 1P Write your name here Surname Other names Pearson Edexcel Certificate Pearson Edexcel International GCSE Centre Number Physics Unit: KPH0/4PH0 Science (Double Award) KSC0/4SC0 Paper: 1P Thursday 15 May

More information

ATOMIC SPECTRA. Apparatus: Optical spectrometer, spectral tubes, power supply, incandescent lamp, bottles of dyed water, elevating jack or block.

ATOMIC SPECTRA. Apparatus: Optical spectrometer, spectral tubes, power supply, incandescent lamp, bottles of dyed water, elevating jack or block. 1 ATOMIC SPECTRA Objective: To measure the wavelengths of visible light emitted by atomic hydrogen and verify the measured wavelengths against those predicted by quantum theory. To identify an unknown

More information

PHYS245 Lab: Special resistors as Sensors: thermistor and photo-resistor

PHYS245 Lab: Special resistors as Sensors: thermistor and photo-resistor Purpose PHYS245 Lab: Special resistors as Sensors: thermistor and photo-resistor To demonstrate that some special resistors can be used as sensors Use a thermistor (a thermal resistor) to sense the temperature

More information

Production of X-rays. Radiation Safety Training for Analytical X-Ray Devices Module 9

Production of X-rays. Radiation Safety Training for Analytical X-Ray Devices Module 9 Module 9 This module presents information on what X-rays are and how they are produced. Introduction Module 9, Page 2 X-rays are a type of electromagnetic radiation. Other types of electromagnetic radiation

More information

SPECTROPHOTOMETRY. Blue. Orange

SPECTROPHOTOMETRY. Blue. Orange Appendix I FV /26/5 SPECTROPHOTOMETRY Spectrophotometry is an analytical technique used to measure the amount of light of a particular wavelength absorbed by a sample in solution. This measurement is then

More information

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Exam Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A photo cathode whose work function is 2.4 ev, is illuminated with white light that has

More information

Experiment #3, Ohm s Law

Experiment #3, Ohm s Law Experiment #3, Ohm s Law 1 Purpose Physics 182 - Summer 2013 - Experiment #3 1 To investigate the -oltage, -, characteristics of a carbon resistor at room temperature and at liquid nitrogen temperature,

More information

Purpose of the experiment

Purpose of the experiment Solar Energy Transfer ENSC 162 Solar Energy Lab Purpose of the experiment Explore the principle of the transfer of heat energy from the sun. Compare and contrast different material for capturing solar

More information

PHYSICS 111 LABORATORY Experiment #3 Current, Voltage and Resistance in Series and Parallel Circuits

PHYSICS 111 LABORATORY Experiment #3 Current, Voltage and Resistance in Series and Parallel Circuits PHYSCS 111 LABORATORY Experiment #3 Current, Voltage and Resistance in Series and Parallel Circuits This experiment is designed to investigate the relationship between current and potential in simple series

More information

LAB 15 PRE-LAB. 2. Complete the table by entering the indicated powers of 1/2. N (1/2) N N (1/2) N

LAB 15 PRE-LAB. 2. Complete the table by entering the indicated powers of 1/2. N (1/2) N N (1/2) N LAB 15 PRE-LAB 1. The plot below shows the height of a tree at different ages. From this graph, determine the age of the tree when its height was: 1.5 m 3.0 m 4.5 m 2. Complete the table by entering the

More information

MCQ - ENERGY and CLIMATE

MCQ - ENERGY and CLIMATE 1 MCQ - ENERGY and CLIMATE 1. The volume of a given mass of water at a temperature of T 1 is V 1. The volume increases to V 2 at temperature T 2. The coefficient of volume expansion of water may be calculated

More information

Intended Learning Outcomes

Intended Learning Outcomes An Introduction to Thermal Radiation This problem provides an introduction to thermal and atmospheric physics. Intended Learning Outcomes By the end of this activity students should be able to: Use basic

More information

Chapter 5 Light and Matter: Reading Messages from the Cosmos

Chapter 5 Light and Matter: Reading Messages from the Cosmos Chapter 5 Light and Matter: Reading Messages from the Cosmos Messages Interactions of Light and Matter The interactions determine everything we see, including what we observe in the Universe. What is light?

More information

PHY 192 Absorption of Radiation Spring

PHY 192 Absorption of Radiation Spring PHY 192 Absorption of Radiation Spring 2010 1 Radioactivity II: Absorption of Radiation Introduction In this experiment you will use the equipment of the previous experiment to learn how radiation intensity

More information

A Theoretical Analysis of the Effect of Greenhouse Gases in the Atmosphere

A Theoretical Analysis of the Effect of Greenhouse Gases in the Atmosphere A Theoretical Analysis of the Effect of Greenhouse Gases in the Atmosphere Michael Hammer A presentation to The Lavoisier Group s 2007 Workshop Rehabilitating Carbon Dioxide held in Melbourne on 29-30

More information

Effect of Temperature on the Resistance of Copper Wire

Effect of Temperature on the Resistance of Copper Wire PHYS-102 Honors Lab 1H Effect of Temperature on the Resistance of Copper Wire 1. Objective The objectives of this experiment are: To demonstrate the effect of temperature on the resistance of copper wire.

More information

1. Theoretical background

1. Theoretical background 1. Theoretical background We consider the energy budget at the soil surface (equation 1). Energy flux components absorbed or emitted by the soil surface are: net radiation, latent heat flux, sensible heat

More information

Spectrophotometry and the Beer-Lambert Law: An Important Analytical Technique in Chemistry

Spectrophotometry and the Beer-Lambert Law: An Important Analytical Technique in Chemistry Spectrophotometry and the Beer-Lambert Law: An Important Analytical Technique in Chemistry Jon H. Hardesty, PhD and Bassam Attili, PhD Collin College Department of Chemistry Introduction: In the last lab

More information

Diode Characteristics

Diode Characteristics by Kenneth A. Kuhn Oct. 3, 2007, rev. Sept. 3, 2009, draft more to come Introduction This paper examines various electrical characteristics of a typical silicon junction diode. Useful mathematical relations

More information

RF Power Measurement. Presented by : Innovation and Technology Commission

RF Power Measurement. Presented by : Innovation and Technology Commission RF Power Measurement Presented by : Standards d and Calibration Laboratory (SCL) Innovation and Technology Commission The Government of the HKSAR Why RF power? Why not RF voltage or current? At radio frequency,

More information

Greenhouse Effect and the Global Energy Balance

Greenhouse Effect and the Global Energy Balance Greenhouse Effect and the Global Energy Balance Energy transmission ( a a refresher) There are three modes of energy transmission to consider. Conduction: the transfer of energy in a substance by means

More information

P R E A M B L E. The problem is run over one week with the following pattern: Facilitated workshop problems for class discussion (2 hours) Lecture

P R E A M B L E. The problem is run over one week with the following pattern: Facilitated workshop problems for class discussion (2 hours) Lecture GREENHOUSE EFFECT AN INTRODUCTION TO THERMAL RADIATION P R E A M B L E The original form of the problem is the first part of a four week (15 credit) module in the IScience programme at the University of

More information

Investigating electromagnetic radiation

Investigating electromagnetic radiation Investigating electromagnetic radiation Announcements: First midterm is 7:30pm on 2/17/09 Problem solving sessions M3-5 and T3-4,5-6. Homework due at 12:50pm on Wednesday. We are covering Chapter 4 this

More information

Electrical Resonance

Electrical Resonance Electrical Resonance (R-L-C series circuit) APPARATUS 1. R-L-C Circuit board 2. Signal generator 3. Oscilloscope Tektronix TDS1002 with two sets of leads (see Introduction to the Oscilloscope ) INTRODUCTION

More information

WAVES AND PARTICLES. (v) i.e (vi) The potential difference required to bring an electron of wavelength to rest

WAVES AND PARTICLES. (v) i.e (vi) The potential difference required to bring an electron of wavelength to rest WAVES AND PARTICLES 1. De Broglie wavelength associated with the charges particles (i) The energy of a charged particle accelerated through potential difference q = charge on the particel (ii) Momentum

More information

III. Radiation and the Greenhouse Effect

III. Radiation and the Greenhouse Effect III. Radiation and the Greenhouse Effect A. The electromagnetic spectrum consists of radiation we can see (visible light, the colors of the rainbow), radiation we can feel (the infrared), radiation we

More information

COLLEGE PHYSICS. Chapter 29 INTRODUCTION TO QUANTUM PHYSICS

COLLEGE PHYSICS. Chapter 29 INTRODUCTION TO QUANTUM PHYSICS COLLEGE PHYSICS Chapter 29 INTRODUCTION TO QUANTUM PHYSICS Quantization: Planck s Hypothesis An ideal blackbody absorbs all incoming radiation and re-emits it in a spectrum that depends only on temperature.

More information

Goals. Introduction R = DV I (7.1)

Goals. Introduction R = DV I (7.1) Lab 7. Ohm s Law Goals To understand Ohm s law, used to describe the behavior of electrical conduction in many materials and circuits. To calculate the electrical power dissipated as heat in electrical

More information

PHOTOELECTRIC EFFECT AND DUAL NATURE OF MATTER AND RADIATIONS

PHOTOELECTRIC EFFECT AND DUAL NATURE OF MATTER AND RADIATIONS PHOTOELECTRIC EFFECT AND DUAL NATURE OF MATTER AND RADIATIONS 1. Photons 2. Photoelectric Effect 3. Experimental Set-up to study Photoelectric Effect 4. Effect of Intensity, Frequency, Potential on P.E.

More information

4.1 SOLAR CELL OPERATION. Y. Baghzouz ECE Department UNLV

4.1 SOLAR CELL OPERATION. Y. Baghzouz ECE Department UNLV 4.1 SOLAR CELL OPERATION Y. Baghzouz ECE Department UNLV SOLAR CELL STRUCTURE Light shining on the solar cell produces both a current and a voltage to generate electric power. This process requires a material

More information

Thermal Diffusivity, Specific Heat, and Thermal Conductivity of Aluminum Oxide and Pyroceram 9606

Thermal Diffusivity, Specific Heat, and Thermal Conductivity of Aluminum Oxide and Pyroceram 9606 Report on the Thermal Diffusivity, Specific Heat, and Thermal Conductivity of Aluminum Oxide and Pyroceram 9606 This report presents the results of phenol diffusivity, specific heat and calculated thermal

More information

PTYS/ASTR 206 Section 2 Spring 2007 Homework #2 (Page 1/5) NAME: KEY

PTYS/ASTR 206 Section 2 Spring 2007 Homework #2 (Page 1/5) NAME: KEY PTYS/ASTR 206 Section 2 Spring 2007 Homework #2 (Page 1/5) NAME: KEY Due Date: start of class 2/6/2007 5 pts extra credit if turned in before 9:00AM (early!) (To get the extra credit, the assignment must

More information

Name Date: Course number: MAKE SURE TA & TI STAMPS EVERY PAGE BEFORE YOU START EXPERIMENT 9. Superconductivity & Ohm s Law

Name Date: Course number: MAKE SURE TA & TI STAMPS EVERY PAGE BEFORE YOU START EXPERIMENT 9. Superconductivity & Ohm s Law Laboratory Section: Last Revised on January 6, 2016 Partners Names: Grade: EXPERIMENT 9 Superconductivity & Ohm s Law 0. Pre-Laboratory Work [2 pts] 1. Define the critical temperature for a superconducting

More information

P150A Experimental Lab #7 Ohm s Law (Ver A 10/12)

P150A Experimental Lab #7 Ohm s Law (Ver A 10/12) Ohm s Law The fundamental relationship among the three important electrical quantities current, voltage, and resistance was discovered by Georg Simon Ohm. The relationship and the unit of electrical resistance

More information

CALIBRATING TOROIDAL CONDUCTIVITY SENSORS

CALIBRATING TOROIDAL CONDUCTIVITY SENSORS Application Data Sheet ADS 43-025 October 2010 Theory CALIBRATING TOROIDAL CONDUCTIVITY SENSORS BACKGROUND A toroidal conductivity sensor consists of two wire wound toroids encased in a plastic body. When

More information

Circuits and Resistivity

Circuits and Resistivity Circuits and Resistivity Look for knowledge not in books but in things themselves. W. Gilbert OBJECTIVES To learn the use of several types of electrical measuring instruments in DC circuits. To observe

More information

INTERFERENCE OF SOUND WAVES

INTERFERENCE OF SOUND WAVES 1/2016 Sound 1/8 INTERFERENCE OF SOUND WAVES PURPOSE: To measure the wavelength, frequency, and propagation speed of ultrasonic sound waves and to observe interference phenomena with ultrasonic sound waves.

More information

Heat Transfer. Phys101 Lectures 35, 36. Key points: Heat as Energy Transfer Specific Heat Heat Transfer: Conduction, Convection, Radiation

Heat Transfer. Phys101 Lectures 35, 36. Key points: Heat as Energy Transfer Specific Heat Heat Transfer: Conduction, Convection, Radiation Phys101 Lectures 35, 36 Heat Transfer Key points: Heat as Energy Transfer Specific Heat Heat Transfer: Conduction, Convection, Radiation Ref: 16-1,3,4,10. Page 1 19-1 Heat as Energy Transfer We often speak

More information

Forms of Energy. Freshman Seminar

Forms of Energy. Freshman Seminar Forms of Energy Freshman Seminar Energy Energy The ability & capacity to do work Energy can take many different forms Energy can be quantified Law of Conservation of energy In any change from one form

More information

Electric Currents. Electric Potential Energy 11/23/16. Topic 5.1 Electric potential difference, current and resistance

Electric Currents. Electric Potential Energy 11/23/16. Topic 5.1 Electric potential difference, current and resistance Electric Currents Topic 5.1 Electric potential difference, current and resistance Electric Potential Energy l If you want to move a charge closer to a charged sphere you have to push against the repulsive

More information

Ohm s Law with Cobra3

Ohm s Law with Cobra3 Related Topics Ohm s law, Resistivity, Contact resistance, Conductivity, Power and Work Principle The relation between voltage and current is measured for different resistors. The resistance is the derivative

More information

Experiment #4, Ohmic Heat

Experiment #4, Ohmic Heat Experiment #4, Ohmic Heat 1 Purpose Physics 18 - Fall 013 - Experiment #4 1 1. To demonstrate the conversion of the electric energy into heat.. To demonstrate that the rate of heat generation in an electrical

More information