Sample Curriculum. Materials Needed. Current Electricity

Transcription

1 Current Electricity Page 1 Sample Curriculum Materials Needed Current Electricity Experiment #1: Electrical Current 3 Experiment #2: Conductors and Insulators 5 Experiment #3: Series and Parallel Circuits 6 Experiment #4: Power Sources in Series and Parallel 9 Experiment #4A: Human Circuits 11 Experiment #5: Let s Blow a Fuse 13 Experiment #6: What s a Diode? 15 Experiment #7: Lemon Battery 16 Experiment #8: Your Ph.D. Circuit 19 Experiment #9: Resistors 21

2 Current Electricity Page 2 Sample Curriculum First: Describe how objects can be grouped according to their properties and categorized according to materials of which they are made; draw conclusions based on observed evidence. Second: Compare and order a set of objects according to a measurementa, and make predictions before measuring. Third: Identify safe and appropriate responses emergencies. Fourth: Classify objects according to two or three properties; classify circuits as series or parallel; predict objects as being conductors or nonconductors of electricity. Sixth: Given a group of materials, classify them as conductors or nonconductors of electricity; predict the effect of removing one or more bulbs in both series and parallel circuits. Experiment 1: Plastic straw, pez candy. Materials Needed Experiment 2: Battery, light bulb, connection cables, plastic straw, glass rod, aluminum strip, wood splint, metal rod, copper wire, other materials students may bring in. Experiment 3: Battery holders (2), 1.5 volt batteries (2), light boards, alligator clips. Experiment 4: Battery holders (4), 1.5 volt AA batteries (4), single pole double throw switch, alligator connectors, light bulb board. Experiment 4a: Class of students divided into two, three, or four groups, jelly beans, poster board, 3x5 cards, a lantern battery, wire, a light bulb. Experiment 5: 3 volt light bulb, alligator clip wire connectors two 1.5 volt AA batteries, single pole double throw switch, fuse wire. Experiment 6: Diode, battery holders (2), connecting cables, 3 volt lamps, two 1.5 volt batteries. Experiment 7: One, two, or three lemons, one high efficiency LED (light emitting diode), alligator clips, zinc strip, copper strip, three paper cups or lemons, and a bottle of real lemon juice. Experiment 8: Two 1.5 volt batteries, connecting wires, high efficiency LED, single pole double throw switch, battery holders, a 2200 microfarad capacitor, various resistors. Experiment 9: One VOM meter, connecting cables, two battery holders, two batteries, 10 ohm resistor, 27 ohm resistor, a switch. Instead of using a VOM meter, one could use an LED or a light bulb and notice the brightness of the light when it is placed parallel to each resistor.

3 Current Electricity Page 3 Current Electricity Experiment #1 Scientific Concept Involved: Today s society is becoming more and more dependent upon electrical power. Electricity is a force which can do work for man, and because it is so easy to transport from one place to another, it is now found in almost every home in the United States. In our homes we use electricity for many things. It is used to warm us and to cook our food (furnaces, ovens, toasters). It is also used to produce light so that we can see at night. Most of us enjoy television and radio which exist solely because of electricity. In this experiment, we are going to use a model to show students what electricity is, how it moves, and how fast it moves. Equipment Needed: Plastic straw, pez candy. Procedure: 1. Bite the end of the straw with your canine teeth until the last ½ inch looks like your dog s favorite chair. 2. Insert the candies into the straw until it is filled. Insert one more, exert pressure, and see what results.. Vocabulary Development: electrons speed (velocity) force conductor Data Collected:

4 Current Electricity Page 4 Questions: 1. Once the straw is filled, what happens each time an additional candy is inserted? 2. What happens if two candies are inserted? 3. How much time lapses between when a candy is inserted and when one comes out? Conclusions: Further Investigations: Cut the straw to a length of 6 inches. Next measure the length of 10 pieces of pez, and from this measurement, calculate the length of one piece of pez. Now determine how many pieces of pez will be needed to fill your 6 inch long straw. A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

5 Current Electricity Page 5 Current Electricity Experiment #2 Scientific Concept Involved: Electricity is very important to us; therefore, it is important that we learn something about the properties of this form of energy. One of the properties of electricity is that it does not travel through every type of matter. By experimenting, we are going to discover what materials electricity travels through easily (conductors) and what materials it does not travel through easily (insulators). Equipment Needed: Battery, light bulb, connection cables, plastic straw, glass rod, aluminum strip, wood splint, metal rod, copper wire, other materials students may bring in. Procedure: Students can learn if a type of matter is an insulator or a conductor by placing the material in question between the two connection cables. If the material is a conductor, the light will come on. If the material is a good conductor, the light will be bright. If the material is an insulator, the light will not come on at all. Have students place the different materials between the connection cables and record their observations in the data sheet. Vocabulary Development: conductor insulator Data Collected: Conductors Insulators

6 Current Electricity Page 6 Questions: 1. Is there any common characteristic of the non-conducting materials? 2. Which material seems to be the best conductor? 3. Are the materials which conduct electricity similar to the materials which hold static charges?? Conclusions: Further Investigations: 1. Does the rust or oxidation on a metal surface cause the metal to be a better conductor than a shiny piece of metal? A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

7 Current Electricity Page 7 Current Electricity Experiment #3 Scientific Concept Involved: Many times it is desirable in a home to connect household items in a circuit so that when one item goes out, the rest of the items in the home are not affected. This experiment will show you what happens when resistive sources are placed in series and in parallel. Equipment needed: Battery holders (2), 1.5 volt batteries (2), light boards, alligator clips. Procedure: First, create a 3 volt battery source by placing two 1.5 volt batteries in series. Next, connect the power source in series with one light bulb. Observe the brightness of the light. Next, connect the power source in series with two light bulbs and again observe the brightness of the light. If you wish, continue by adding additional light bulbs and observing the brightness of the light. Now create a parallel resistive circuit by using the same power source as used above, but this time place one, then two, and finally three light bulbs in parallel with the power source, as shown in the diagram. Vocabulary Development: parallel series light intensity Data Collected:

8 Current Electricity Page 8 Questions: 1. What happens to the brightness of the bulbs when they are placed in series? 2. What happens to the brightness of the bulbs when they are placed in parallel? 3. Why do you think this happens? 4. Unscrew one of the light bulbs in the series connection. What happens? 5. Unscrew one of the light bulbs in the parallel connection and observe what happens.. What is the advantage of this type of connection in your home? Conclusions: Further Investigations: Can you create a circuit with lamps placed in both parallel and series in the same circuit? First try to anticipate how many batteries you will need in order to have every lamp work properly. You might wish to diagram your circuit first using the proper symbols. A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

9 Current Electricity Page 9 Current Electricity Experiment #4 Scientific Concept Involved: We will try to discover what happens when power sources are placed in series and in parallel. Equipment Needed: Battery holders (4), 1.5 volt AA batteries (4), single pole double throw switch, alligator connectors, light bulb board. Procedure: Connect one battery in series with a switch and a light bulb. Observe the intensity of the light. Next, Place two batteries in series in the same circuit and again observe the intensity of the light. Next place four battery holders together in a parallel arrangement and connect this parallel power supply in series with your switch and your light bulb. Again observe the intensity of the light. Vocabulary Development: series parallel intensity Data Collected:

10 Current Electricity Page 10 Questions: 1. What happens to the intensity of the light when batteries are added in series? 2. What happens to the intensity of the light when batteries are added in parallel? 2. What do you think is the advantage of each circuit? (Hint: see below.) Conclusions: Further Investigations: What is the length of time the light bulb burns in the above series connection compared to the length of time it burns in the above parallel connection? A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

11 Current Electricity Page 11 Scientific Concept Involved: Current Electricity Experiment #4A This is another way of doing experiments 1-4 that involves the students in more team effort. The conducting cables are the individual students. Solder connections are made when the students touch feet. Paper cups behave like electrons. Each cup has within it a jelly bean which acts like an energy source. When the left or right hand receives a paper cup, it must immediately be passed to the other hand. Neck signs will be used to identify the electrical components involved. If a student is a power supply, he/she must remove a jelly bean from the energy source bag, place it in a cup, and start passing it around the circuit. Consumers are the only individuals allowed to eat the jelly beans. Switches must place their feet close together and hold their hands across their chests when they are off; they must drop their hands and touch feet when they are on. An insulator must have his/her hands tied so they cannot pass the cups. With these instructions the class is to construct the following circuits. Equipment Needed: Class of students divided into two, three, or four groups, jelly beans, poster board, 3x5 cards, a lantern battery, wire, a light bulb. Procedure: Using the above rules, set up each of the circuits shown above. After you have completed the human circuit, have the students actually wire the same circuit using the wire, battery, and light bulb. Vocabulary Development: electrons circuit parallel series switch conductor battery Data Collected:

12 Current Electricity Page 12 Questions: 1. What is the purpose of a switch? 2. What is the purpose of a conductor? 3. How does a parallel circuit differ from a series circuit? 4. How did the electroscope become charged? Conclusions: Further Investigations: What do you think would happen to the brightness of the bulbs if you were to connect the lamps in the following circuits? A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

13 Current Electricity Page 13 Current Electricity Experiment #5 Scientific Concept Involved: All electronic circuits found in our homes have four basic components. In this laboratory exercise we will construct a simple circuit involving a light bulb (resistance device) a wire (conductor), a battery (power source), a fuse and a switch (controlling device). Equipment Needed: 3 volt light bulb, alligator clip wire connectors two 1.5 volt AA batteries, single pole double throw switch, fuse wire. Procedure: Construct a series connection like the one in the diagram using all of the items listed above. The fuse is one of the small strands of wire removed from a piece of zip cord or steel wool pad. Place a shunt wire across the light bulb and observe what happens. The shunt wire can be one of the alligator clip cables. Vocabulary Development: resistance conductors simple circuit fuse switch Data Collected:

14 Current Electricity Page 14 Questions: 1. Which leads do you have to use on the switch in order to get the light bulbs to light? 2. When you shunt the light bulb, what happens to the circuit? 3. When you remove the shunt, what happens to the light bulb? Why? 4. What is the purpose of the fuse? Conclusions: Further Investigations: What would happen to the protection capabilities of a fuse wire if it were made from a larger diameter wire? A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

15 Current Electricity Page 15 Scientific Concept Involved: Current Electricity Experiment #6 A number of years ago traditional electronics changed with the advent of the solid state transistor. This revolutionary concept of how to create devices which used to be housed in vacuum tubes allowed man to miniaturize electronic devices and thereby maximize energy efficiency. Since that time we have seen electron tubes almost disappear and solid state devices like transistors, integrated circuits, and diodes multiply. Today they are found in every imaginable electronic device. In this laboratory we will investigate a diode, one of the simpler solid state components found in many home components. You will try to determine the way a diode must be placed in a simple circuit in order for it to work. Equipment Needed: Diode, battery holders (2), connecting cables, 3 volt lamps, two 1.5 volt batteries. Procedure: 1. Set up the above circuit. 2. Before you place the diode between the two connecting clips, note the band on the diode. This band indicates that the diode, like many electronic devices, is polarized and must be placed in the circuit in the proper direction. Your job is to place the diode in the circuit so as to turn on the lamp. Vocabulary Development: diode polarity forward bias solid state silicon Data Collected: Forward bias diode Reverse bias diode Observation: Observation:

16 Current Electricity Page 16 Questions: 1. Which end of the diode must be attached to the positive side of the battery in order to turn on the lamp? 2. Would one battery turn on the diode? 3. Describe what a diode does in a circuit. Conclusions: Further Investigations: If you can get access to a DC power supply, try to determine what minimum voltage is necessary to turn on a diode. A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

17 Current Electricity Page 17 Current Electricity Experiment #7 Scientific Concept Involved: We will show students how to construct a lemon battery. Equipment Needed: One, two, or three lemons, one high efficiency LED (light emitting diode), alligator clips, zinc strip, copper strip, three paper cups or lemons, and a bottle of real lemon juice. Procedure: Insert one piece of zinc and one piece of copper into a lemon or cup filled with diluted lemon juice. Now connect the LED in series with the lemon juice by using alligator clips. Observe the LED. If it does not light, change the polarity of the LED and/or connect another lemon battery in series with the first and again observe the LED. Continue doing this until you have decided the experiment is a lemon or the LED lights. Vocabulary Development: electrodes electrolytes ions Data Collected:

18 Current Electricity Page 18 Questions: 1. The + side of the LED must be attached to which type of metal before the LED will light? 2. Since the LED requires approximately 1.7 volts before it will light, what happens to the voltage as we series connect lemon batteries? 3. If the voltage is greater than 1.7 volts and the current is approximately two milliamperes, the LED will glow brightly. What physical feature of this lemon battery produces the necessary current? Conclusions: Further Investigations: Do you think it would take more or less lemon batteries if we were to use different types of metal strips? A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

19 Current Electricity Page 19 Current Electricity Experiment #8 Scientific Concept Involved: Another electronic device which is used today on almost every electronic printed circuit board is the capacitor. There are many types of capacitors used in both AC and DC circuits; however, they all have as their primary function the ability to store energy. In this experiment you will work with a DC electrolytic capacitor and observe its ability to store energy. Equipment Needed: Two 1.5 volt batteries, connecting wires, high efficiency LED, single pole double throw switch, battery holders, a 2200 microfarad capacitor, various resistors. Procedure: Create the circuit shown in the above electronic schematic. The circuit is designed so that when the switch is in position A, the batteries are in series with the capacitor and the capacitor is therefore being charged. When the switch is moved to position B, the batteries are in effect removed from the circuit; the LED is now in series with the capacitor, which is therefore being discharges. To discharge the capacitor at a slower rate, you might wish to place a resistor in series with the capacitor. The value of the resistor can be anywhere from 100 ohms to 1K ohm. Vocabulary Development: charged discharged capacitor SPDT switch Data Collected:

20 Current Electricity Page 20 Questions: 1. Was there any observable difference when the circuit was in position A? 2. Was there any observable difference when the circuit was in position B? 3. Can you give the reason for what you observed in answering the previous question? Conclusions: Further Investigations: What do you think would happen if you used a larger or a smaller capacitor? A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?

21 Current Electricity Page 21 Scientific Concept Involved: Current Electricity Experiment #9 Another electronic component found frequently on printed circuit boards is the resistor. This component does exactly what its name implies. That is, it resists the flow of electrons. This means that if you wished to push the same number of electrons (current) through a resistor of higher value, more push (voltage) would be required. In this experiment we will try to measure the resistance, the current, and the voltage across a resistance using a VOM meter. This meter is capable of measuring voltage, current, and resistance. Voltage is measured in volts, current is measured in amperes, and resistance is measured in ohms. Equipment Needed: One VOM meter, connecting cables, two battery holders, two batteries, 10 ohm resistor, 27 ohm resistor, a switch. Instead of using a VOM meter, one could use an LED or a light bulb and notice the brightness of the light when it is placed parallel to each resistor. Procedure: Using the schematic above, connect the various components. Now connect the VOM meter across resistor 1 and measure the voltage drop across the resistor. Next place the VOM meter across resistor 2 and measure its voltage drop. If you do not have a VOM meter, you may use the LED or light bulb and record the relative brightness of the light emitted. Next open the circuit at point A and use the VOM meter to measure the current in the circuit. You might try to open the circuit at other points and also measure the current at these points as well. Remember that an LED requires approximately 15 milliamperes in order to work! Vocabulary Development: voltage current resistor Data Collected:

22 Current Electricity Page 22 Questions: 1. Across which resistor was the voltage higher? How do you know? 2. Did the current change as you moved the current meter around the circuit? Explain. Conclusions: Further Investigations: What do you think would happen if you were to use resistors of the same values? If you have access to a VOM meter and measure the voltage drop across each resistor, you will have better results. A. Application to everyday life and to other disciplines: B. Pitfalls to avoid when doing the experiment: C. Comments: D. Best grade level?