Answer, Key Homework 11 David McIntyre 1 1 A


 Dylan Blake
 2 years ago
 Views:
Transcription
1 nswer, Key Homework 11 avid Mcntyre 1 This printout should have 36 questions, check that it is complete. Multiplechoice questions may continue on the next column or page: find all choices before making your selection. The due time is entral time. hapters 27 and 28 problems. 001 (part 1 of 1) 0 points t is known that about one electron per atom of copper contributes to the current. The atomic mass of copper is g and its density is 8.92 g/cm 3. alculate the average drift speed of electrons traveling through a copper wire with a crosssectional area of 1 mm 2 when carrying a current of 1 (values similar to those for the electric wire to your study lamp). orrect answer: m/s. Given : N = 1, M = g, ρ = 8.92 g/cm 3, = 1 mm 2 = m 2, = 1, and q e = /electron. We first calculate n, the number of currentcarrying electrons per unit volume in copper. ssuming one free conduction electron per atom, n = N ρ M, where N is vogadro s number and ρ and M are the density and the atomic weight of copper, respectively n = n ( 1 electron atom ) N ρ M. ( 1 electron ) atoms atom g (8.92 g/cm 3) ( 10 6 cm 3 ) 1 m 3 = electrons/m 3. The drift speed is v d, v d = n q e = electrons/m 3 1 ( /electron) 1 ( m 2 ) = m/s. 002 (part 1 of 3) 0 points The damage caused by electric shock depends on the current flowing through the body; 1 m can be felt and 5 m is painful. bove 15 m, a person loses muscle control, and 70 m can be fatal. person with dry skin has a resistance from one arm to the other of about Ω. When skin is wet, the resistance drops to about 5300 Ω. What is the minimum voltage placed across the arms that would produce a current that could be felt by a person with dry skin? orrect answer: 100 V. Given : min = 1 m, and R dry = Ω. The minimum voltage depends on the minimum current for a given resistance, so V min = min R dry ( ) 1 = (1 m) ( Ω) 1000 m = 100 V. 003 (part 2 of 3) 0 points Using the same electric potential as in Part 1, what would be the current if the person had wet skin? orrect answer: m. Given : V min = 100 V, and R wet = 5300 Ω.
2 nswer, Key Homework 11 avid Mcntyre 2 For the voltage V from Part 1 and the resistance R wet, = V min R wet = 100 V ( ) 1000 m 5300 Ω 1 = m. 004 (part 3 of 3) 0 points What would be the minimum voltage that would produce a current that could be felt when the skin is wet? orrect answer: 5.3 V. Given : min = 1 m, and R wet = 5300 Ω. V 1 = min R wet ( ) 1 = (1 m) (5300 Ω) 1000 m = 5.3 V. 005 (part 1 of 4) 0 points f the current carried by a metallic conductor is doubled, (a) What happens to the charge carrier density? ssume that the temperature of the metallic conductor remains constant. 1. t quadruples. 2. t is unchanged. correct 3. t is quartered. 4. t is halved. 5. t doubles. asic oncept: J = σ = n q v d v d = q m τ. Solution: The charge carrier density n is unaffected. This is simply a property of the material, and is related to the mass density and the number of valence electrons available per atom. 006 (part 2 of 4) 0 points (b) What happens to the current density? 1. t doubles. correct 2. t is unchanged. 3. t is quartered. 4. t quadruples. 5. t is halved. The current density J = only depends on the current and the crosssectional area of the conductor, so if doubles and remains the same, J must also double: J = 2 = 2 = 2 J. 007 (part 3 of 4) 0 points (c) What happens to the electron drift velocity? 1. t is unchanged. 2. t is halved. 3. t is quartered. 4. t quadruples. 5. t doubles. correct The electron drift velocity v d is given by v d = n q, where q is the charge of an electron. So if doubles, v d must also double: v d = 2 n q = 2 n q = 2v d.
3 nswer, Key Homework 11 avid Mcntyre (part 4 of 4) 0 points (d) What happens to the average time between collisions? 1. t doubles. 2. t is halved. 3. t is quartered. 4. t is unchanged. correct 5. t quadruples. The average time τ between collisions is given by τ = v d m q, where m is the mass of an electron and is the applied electric field (determined by Ohm s Law: J = σ ). Substituting for, τ = v d m σ q J. Since v d and J are each multiplied by a factor of two, the factors of two cancel (as long as σ does not change due to heating). ll the other variables remain the same (as long as σ does not change due to heating). Therefore τ remains unchanged. 009 (part 1 of 2) 0 points The circuit below shows four identical bulbs connected to an ideal battery, which has negligible internal resistance. Rank the bulbs in order from brightest to dimmest. 1. > > > 2. = > = V 3. > = > 4. = > > 5. = > = correct 6. = = = 7. = > = 8. > = > 9. > > > 10. = = > From the figure, the total resistance of the circuit is 2 R + R 2 = 5 R 2. Then = = V 5 R 2 = 2 5 V R = 0.4 V R = = 1 2 = 1 V 5 R = 0.2V R The rankings of the currents are also the corresponding rankings of the brightness. 010 (part 2 of 2) 0 points Suppose a switch has been added to the circuit as shown. The switch is initially closed. V When the switch is opened, what happens to the currents through bulbs,, and? 1. decreases, remains the same, decreases. 2. remains the same, decreases, remains the same 3. increases, increases, increases.
4 nswer, Key Homework 11 avid Mcntyre 4 4. remains the same, increases, remains the same. 5. decreases, increases, decreases. correct 6. remains the same, remains the same, remains the same. 7. increases, remains the same, decreases. 8. increases, remains the same, increases. 9. increases, decreases, increases. 10. decreases, decreases, decreases. With the switch open, the total resistance of the circuit is 3 R, so = = = V 3 R = 0.33V R This is to be compared with the case that the switch is closed, where from previous part, = = 0.4 V R and = 0.2 V R. So for the present case, and decrease and increases. 011 (part 1 of 4) 0 points battery has an emf of 12 V and an internal resistance of 0.13 Ω. ts terminals are connected to a load resistance of 2 Ω. Find the current in the circuit. orrect answer: Given : = 12 V, R = 2 Ω, and r = 0.13 Ω. The total resistance is R + r, so = R + r 12 V = 2 Ω Ω = (part 2 of 4) 0 points alculate the terminal voltage of the battery. orrect answer: V. The terminal voltage V of the battery is equal to V r = r = 12 V ( ) (0.13 Ω) = V. 013 (part 3 of 4) 0 points Find the power dissipated in the load resistor. orrect answer: W. The power dissipated in the load resistor is P R = 2 R = ( ) 2 (2 Ω) = W. 014 (part 4 of 4) 0 points Find the power dissipated in the battery. orrect answer: W. The power dissipated in the battery is P r = 2 r = ( ) 2 (0.13 Ω) = W. 015 (part 1 of 2) 0 points n the figure below the switch S is initially in position 1. Given, = R 2 = R 3. Neglect the internal resistance of the battery.
5 nswer, Key Homework 11 avid Mcntyre V S 0 R 2 as when was in the circuit. Since R 2 and R 3 have the same terminal voltage and resistance, the current through R 2 and R 3 must now be the same. 017 (part 1 of 1) 0 points onsider the following circuit containing identical bulbs. What happens to the current through R 3 when the switch is moved to the open position The current through R 3 decreases to twothirds its original value. V 2. The current through R 3 increases to twice its original value. 3. The current through R 3 increases to threehalves its original value. 4. The current through R 3 is reduced to onehalf its original value. 5. The current through R 3 remains the same. correct The voltage across R 3 is the of the battery, and is unchanged. The current through R 3 remains the same,. R (part 2 of 2) 0 points What happens when switch S is moved to position 3, leaving R 2 and R 3 parallel? 1. The current through R 2 is half what it was with in the circuit. 2. The current through R 2 and R 3 are now the same. correct 3. The current through R 3 increases. 4. The current through R 3 decreases. 5. The current through R 2 remains the same 1. = = = = 2. = = > = 3. = > = = 4. = = > = correct 5. = = > > 6. = > = = 7. = > > = 8. = = > > 9. > > > > 10. = > > = The potential across bulbs, and is V. The potential across bulbs and is V 2. Thus i = i = i = V R i = i = V 2R. 018 (part 1 of 2) 0 points Four identical light bulbs are connected either in series (circuit 1) or parallel (circuit 2)
6 nswer, Key Homework 11 avid Mcntyre 6 to a constant voltage battery with negligible internal resistance, as shown. We can see that the bulbs in circuit 2 are more than 4 times brighter than the bulbs in circuit (part 2 of 2) 0 points f one of the bulbs in circuit 2 is unscrewed and removed from its socket, the remaining 3 bulbs 1. go out. circuit 1 2. are unaffected. correct 3. become brighter. 4. become dimmer. circuit 2 ompared to the individual bulbs in circuit 1, the individual bulbs in circuit 2 are 1. the same brightness as bright. 3. less than 1 4 as bright times brighter. 5. more than 4 times brighter. correct Solution: n circuit 1, the voltage across each light bulb is V = R = 4 R R = 4, so the power of each bulb in circuit 1 is P 1 = V 2 R = 2 16 R. n circuit 2, the voltage across each bulb is identical; namely. Hence the power of each bulb in circuit 2 is P 2 = 2 R = 1 16 P 1. Since the bulbs are parallel, after one of the bulbs is unscrewed, the voltage across each remaining bulb is unchanged, and the brightness is unaffected. 020 (part 1 of 3) 0 points Hint: pply the Kirchhoff s law to the loop. Given: 2 = 2 R 4 = R 2 = R 3, = r. is the current entering and leaving the circuit. ach current shown in the figure is denoted by the same subscript as the resistor through which it flows (e.g., i 1 is the current flowing through ). R 2 i 1 Find the ratio i i 1 = 2 correct 2. i 1 = 1 3 i5 i 3 R 4 R 3 i 4
7 nswer, Key Homework 11 avid Mcntyre 7 3. i 1 = 3 4. i 1 = 1 5. i 1 = i 1 = i 1 = 4 Given : = r, R 2 = 2 r, R 3 = 2 r, R 4 = r. r 2 r and 4. i 5 = 3 correct 5. i 5 = 2 6. i 5 = 5 7. i 5 = 7 8. i 5 = 4 i 1 = 2 = i 1 + = 2 + = 3 = 3 i 1 = r i 1 i5 i 3 r i 4 Following a similar analysis, one finds that i 4 = 2, so that i 3 = i 3 3 and i 4 = 2 3. Note: The junction equation at is asic oncept: ircuit. Solution: ased on Kirchhoff s law, the equation for the loop is given by i 1 + R 2 = 0 i 1 = R 2 = 2 r r = (part 2 of 3) 0 points Find the magnitude of the current i 5 which flows from to. 1. i 5 = 0 2. i 5 = 8 3. i 5 = 6 + i 5 = i 4 i 5 = i 4, or = i 3 i 1 = = 3 i 5 = (part 3 of 3) 0 points Find the resistance R. 1. R = 3 r 2. R = 0 3. R = r 4. R = 2 r 5. R = 4 3 r correct
8 nswer, Key Homework 11 avid Mcntyre 8 6. R = 1 3 r 7. R = 2 3 r etermine, i.e. points and correct the current between 8. R = 3 2 r R = 5 3 r y inspection, the following circuit is equivalent to the original circuit R Here R 2 R 4 R = 2 R 2 = 2 2 r2 r + 2 r = 4 3 r 023 (part 1 of 3) 0 points onsider a cubic resistor network shown, where all the resistors are the same. ach resistor has a resistance r. current comes into the network at. The same current leaves the network at asic oncept: Symmetry in circuits. Solution: Go through the network systematically from to. The current enters at. Since the network is completely symmetric, there can be no difference in resistance for the three possible paths the current can split into at. Thus, each of the three must carry identical current, and they must add up to (since no current is lost at the junction): = (part 2 of 3) 0 points etermine, i.e. the current between points and
9 nswer, Key Homework 11 avid Mcntyre correct 7. 3 Now we are at. The current coming in from has two possible choices of path, and again there is complete symmetry between the two. Thus the current going through splits in half: = 2 = (part 3 of 3) 0 points etermine R, i.e. the effective resistance between points and. 1. r 3 2. r r 6 correct 4. r 2 5. r 6. 4r r r r 6 Finally, we calculate the equivalent resistance. We can step through the path to find the potential V between and. Kirchoff s Laws tell us that each time we cross a resistor (moving with the current) we drop a potential V = R. Therefore V V = r + r + r Now note that = by symmetry, so ( V V = V = r ) = r Now V = R, so R = 5 6 r 026 (part 1 of 2) 0 points Two identical light bulbs and are connected in series to a constant voltage source. Suppose a wire is connected across bulb as shown. ulb V 1. will burn half as brightly as before. 2. will burn as brightly as before. 3. will burn nearly four times as brightly as before. correct 4. will burn twice as brightly as before. 5. will go out. The electric power is given by P = 2 R = V 2 R. efore the wire is connected, = = V 2 R so that P = V 2 4 R. fter the wire is connected, = V R and = 0, so = 0 P = V 2 R = 4 P.
10 nswer, Key Homework 11 avid Mcntyre (part 2 of 2) 0 points and bulb 1. will burn nearly four times as brightly as before. 2. will burn half as brightly as before. 3. will go out. correct 4. will burn as brightly as before. 5. will burn twice as brightly as before. Since there is no potential difference between the two ends of bulb, it goes off. 028 (part 1 of 3) 0 points onsider the circuit shown below. 1 r 1 Recall that Kirchhoff s loop rule states that the sum of the potential differences across all the elements around a closed circuit loop is zero. f a resistor is traversed in the direction of the current, the change in potential is R. f a emf source is traversed from the to + terminals, the change in potential is +. pply the opposite sign for traversing the elements in the opposite direction. Hence, by inspection : r 2 i 1 r 1 = (part 2 of 3) 0 points What equation does the loop F yield? 1. 2 r 2 + i R = r 2 i R = r 2 i R = r 2 i R = 0 correct i 1 2 r 2 F R i pply Kirchhoff s rules. does the loop yield? What equation r 2 i R = r 2 + i R = r 2 + i R = 0 F : 2 i R r 2 = r 2 + i 1 r 1 = r 2 i 1 r 1 = r 2 i 1 r 1 = r 2 + i 1 r 1 = r 2 + i 1 r 1 = r 2 i 1 r 1 = 0 correct r 2 i 1 r 1 = (part 3 of 3) 0 points Let: 1 = 2 =, and r 1 = r 2 = r, where = 9 V and r = 2.4 Ω. lso R = 4.1 Ω. Hint: From symmetry, one expects i 1 =. Find the current i. orrect answer: Given : 1 = 2 = = 9 V, r 1 = r 2 = 2.4 Ω, and R = 4.1 Ω. We are given that 1 = 2 and r 1 = r 2. This implies that i 1 =. (Why? Look at the loops
11 nswer, Key Homework 11 avid Mcntyre 11 F and F and see if there are any similarities.) Hence the junction rule yields i 1 + = 2 = i =. Substituting this into the loop equation F, Solving for i yields 2 i R r 2 = 0 i = 2 R + r V = 4.1 Ω Ω 2 = (part 1 of 3) 0 points onsider the circuit shown below, the capacitor is initially uncharged. R 2 S b fter S is switched to position a, the initial current through is 1. t=0 = R 2 V o 2. t=0 = V o 3. t=0 = V o 4. t=0 = R 2 V o 5. t=0 = R 2 6. t=0 = V o R 2 V o a 7. t=0 = ( ) V o 8. t=0 = V o correct When the switch is in position a at t = 0, there is no potential drop across the capacitor. Note: There is no current flowing through R 2, so the entire potential drop, V o, is across the resistor. From Ohm s law, = V o. 032 (part 2 of 3) 0 points Leave the switch at position a for a long time, then move the switch from a to b. When the switch is in position b, what is the time constant, τ, of the circuit? 1. τ = 2. τ = 3. τ = R 2 4. τ = R 2 5. τ = R 2 ( ) 6. τ = ( ) 7. τ = R 2 8. τ = R 2 9. τ = R τ = ( ) correct When the switch is in position b, and R 2 are now in series so the equivalent resistance is R =. y definition, the time constant is τ = R = ( ).
12 nswer, Key Homework 11 avid Mcntyre (part 3 of 3) 0 points Let: V o = 9 V, = 1 µf, = 7 Ω, and R 2 = 20 Ω. t a time 3 τ after S has been switched to 2 position b, what is the power consumption of the circuit? orrect answer: W. The switch on the circuit is closed at t = 0. Find the charge on the capacitor at 4.73 s. orrect answer: µ. Given : t = 4.73 s, R = 1.1 MΩ = Ω, = 1.4 µf = F, = 14.7 V. and Given : V o = 9 V, = 1 µf, = 7 Ω, R 2 = 20 Ω. and While the capacitor is discharging, the magnitude of the current decreases as a function of time as R S (t) = V o e t/τ. Noting that R =, the power consumed by the circuit at t = 3 2 τ is P = 2 ( ) [ ] 2 V o = e 3/2 ( ) Vo 2 = e 3 (9 V)2 = 7 Ω + 20 Ω e 3 = W. 034 (part 1 of 3) 0 points Given: The R circuit in the figure below. 1.1 MΩ 14.7 V 1.4 µf S t t = 4.73 s, t/(r q = (1 e )) = ( F)(14.7 V) { [ ]} 4.73 s 1 exp ( Ω) ( F) = = µ. 035 (part 2 of 3) 0 points Find the current in the resistor at 4.73 s. orrect answer: µ. t t = 4.73 s, = ) e t/(r R = 14.7 V Ω [ ] 4.73 s exp ( Ω) ( F) = = µ. 036 (part 3 of 3) 0 points
13 nswer, Key Homework 11 avid Mcntyre 13 t 4.73 s the current in the resistor is (Part 2) and the charge on the capacitor is q (Part 1). What is the power delivered by the battery? orrect answer: µw. n the time interval t, work done by the battery in pushing charge q across the battery is W battery = q. orrespondingly, the power is d W battery dt = dq dt =. The power dissipated in a resistor is d W resistor dt = 2 R. The power to create the electric field in a capacitor is d W capacitor dt = q. Thus the total power dissipated in the capacitor and resistor, that is the power delivered by the battery is d W battery dt ( = R + q ) = ( ) [ ( ) ( Ω) + ( ) ( F) = W = µw. ]
Physics 9 Fall 2009 Homework 6  Solutions
. Chapter 32  Exercise 8. Physics 9 Fall 29 Homework 6  s How much power is dissipated by each resistor in the figure? First, let s figure out the current in the circuit. Since the two resistors are
More informationCircuits. PHY2049: Chapter 27 1
Circuits PHY2049: Chapter 27 1 What You Already Know Nature of current Current density Drift speed and current Ohm s law Conductivity and resistivity Calculating resistance from resistivity Power in electric
More information1 of 8 3/30/2010 2:18 PM
1 of 8 3/30/2010 2:18 PM Chapter 32 Homework Due: 8:00am on Tuesday, March 30, 2010 Note: To understand how points are awarded, read your instructor's Grading Policy. [Return to Standard Assignment View]
More informationThe Electric Circuits Concept Evaluation (ECCE) 1. A bulb and a battery are connected as shown below.
The Electric ircuits oncept Evaluation (EE) DIRETIONS: Write your name, class and date above, and on the answer sheet. nswer questions 145 on the answer sheet by filling in the circle corresponding to
More information= (0.400 A) (4.80 V) = 1.92 W = (0.400 A) (7.20 V) = 2.88 W
Physics 2220 Module 06 Homework 0. What are the magnitude and direction of the current in the 8 Ω resister in the figure? Assume the current is moving clockwise. Then use Kirchhoff's second rule: 3.00
More informationElectric circuits, Current, and resistance (Chapter 22 and 23)
Electric circuits, Current, and resistance (Chapter 22 and 23) Acknowledgements: Several Images and excerpts are taken from College Physics: A strategic approach, Pearson Education Inc Current If electric
More informationphysics 112N current, resistance and dc circuits
physics 112N current, resistance and dc circuits current! previously we considered electrostatic situations in which no Efield could exist inside a conductor! now we move to the case where an electric
More informationKirchhoff's Rules and Applying Them
[ Assignment View ] [ Eðlisfræði 2, vor 2007 26. DC Circuits Assignment is due at 2:00am on Wednesday, February 21, 2007 Credit for problems submitted late will decrease to 0% after the deadline has passed.
More informationLecture PowerPoints. Chapter 19 Physics: Principles with Applications, 7th edition Giancoli
Lecture PowerPoints Chapter 19 Physics: Principles with Applications, 7th edition Giancoli This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching
More informationFREQUENTLY ASKED QUESTIONS October 2, 2012
FREQUENTLY ASKED QUESTIONS October 2, 2012 Content Questions Why do batteries require resistors? Well, I don t know if they require resistors, but if you connect a battery to any circuit, there will always
More informationMC Electricity Resistors Review
2. In the circuit shown above, what is the value of the potential difference between points X and Y if the 6 volt battery has no internal resistance? (A) 1 V (B) 2 V (C) 3 V (D) 4 V (E) 6V 8. The circuit
More informationCircuits. The light bulbs in the circuits below are identical. Which configuration produces more light? (a) circuit I (b) circuit II (c) both the same
Circuits The light bulbs in the circuits below are identical. Which configuration produces more light? (a) circuit I (b) circuit II (c) both the same Circuit II has ½ current of each branch of circuit
More informationThe content contained in sections 1 4, 6 9, 11 13, and 15 of chapter 20 of the textbook is included on the AP Physics B exam.
hapter 0 Electric ircuits hapter 0 ELETR RUTS PREVEW onventional current is the flow of positive charges though a closed circuit. The current through a resistance and the voltage which produces it are
More informationAP Physics Electricity and Magnetism #4 Electrical Circuits, Kirchoff s Rules
Name Period AP Physics Electricity and Magnetism #4 Electrical Circuits, Kirchoff s Rules Dr. Campbell 1. Four 240 Ω light bulbs are connected in series. What is the total resistance of the circuit? What
More informationHomework 6 Solutions PHYS 212 Dr. Amir
Homework 6 Solutions PHYS Dr. Amir Chapter 5: 9. (II) A 00W lightbulb has a resistance of about Ω when cold (0 C) and 0 Ω when on (hot). Estimate the temperature of the filament when hot assuming an average
More informationChapter 7 DirectCurrent Circuits
Chapter 7 DirectCurrent Circuits 7. Introduction...77. Electromotive Force...73 7.3 Resistors in Series and in Parallel...75 7.4 Kirchhoff s Circuit Rules...77 7.5 VoltageCurrent Measurements...79
More informationHow many laws are named after Kirchhoff?
Chapter 32. Fundamentals of Circuits Surprising as it may seem, the power of a computer is achieved simply by the controlled flow of charges through tiny wires and circuit elements. Chapter Goal: To understand
More informationElectric 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 informationChapter 19 DC Circuits
Lecture PowerPoints Chapter 19 Physics: Principles with Applications, 6 th edition Giancoli Chapter 19 DC Circuits 2005 Pearson Prentice Hall This work is protected by United States copyright laws and
More informationChapter 11. Circuits
Chapter 11 Circuits 376 377 AP Physics Multiple Choice Practice Circuits 1. Multiple Correct. Which two arrangements of resistors shown above have the same resistance between the terminals? Select two
More informationCapacitance, Resistance, DC Circuits
This test covers capacitance, electrical current, resistance, emf, electrical power, Ohm s Law, Kirchhoff s Rules, and RC Circuits, with some problems requiring a knowledge of basic calculus. Part I. Multiple
More informationCHAPTER 28 ELECTRIC CIRCUITS
CHAPTER 8 ELECTRIC CIRCUITS 1. Sketch a circuit diagram for a circuit that includes a resistor R 1 connected to the positive terminal of a battery, a pair of parallel resistors R and R connected to the
More informationElectric Currents & DC Circuits
Slide 1 / 70 Slide 2 / 70 1 The length of an aluminum wire is quadrupled and the radius is doubled. y which factor does the resistance change? lectric urrents & ircuits 2 4 1/2 1/4 1 Slide 3 / 70 2 copper
More informationElectrostatics. Electrostatics Version 2
1. A 150watt lightbulb is brighter than a 60.watt lightbulb when both are operating at a potential difference of 110 volts. Compared to the resistance of and the current drawn by the 150watt lightbulb,
More informationRecitation 6 Chapter 21
Recitation 6 hapter 21 Problem 35. Determine the current in each branch of the circuit shown in Figure P21.35. 3. Ω 5. Ω 1. Ω 8. Ω 1. Ω ɛ 2 4 12 Let be the current on the left branch (going down), be the
More informationMULTIPLE 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. 1) If the voltage at a point in space is zero, then the electric field must be A) zero. B) positive.
More informationelectrons/s
CURRNT, RSISTANC, AND DIRCTCURRNT CIRCUITS 9 Answers to MultipleChoice Problems. B 2. B 3. D 4. B, D 5. A 6. A 7. C 8. A 9. C 0. C. C 2. C 3. C 4. A 5. Solutions to Problems 9.. Set Up: A 5 C/s. An electron
More informationPart 1. Part 1. Electric Current. and Direct Current Circuits. Electric Current. Electric Current. Chapter 19. Electric Current
Electric Current Electric Current and Direct Current Circuits Chapter 9 Resistance and Ohm s Law Power in Electric Circuits Direct Current Circuits Combination Circuits Real life is mostly dynamic Part
More informationCurrent, Resistance and DC Circuits
E1  Current and Current Density Chapter E Current, Resistance and DC Circuits Blinn College  Physics 2426  Terry Honan Basic Definitions If Q is the charge that passes through some surface, usually
More informationEMF and Terminal Voltage Resistors in Series and Parallel Kirchhoff s Rules EMFs in Series and Parallel; Charging a Battery Circuits with Capacitors
Chapter 19 DC Electrical Circuits Topics in Chapter 19 EMF and Terminal Voltage Resistors in Series and Parallel Kirchhoff s Rules EMFs in Series and Parallel; Charging a Battery Circuits with Capacitors
More informationElectric current II. Except in a superconductor
Electric current Charges in motion: Count positive charges going from left to right Add negative charges going from right to left Subtract all charges moving in the opposite direction Divide by time =>
More informationChapter 18 Electric Current and Circuits
Chapter 18 Electric Current and Circuits 3. When a current flows down a wire: A. electrons are moving in the direction of the current. B. electrons are moving opposite the direction of the current. C.
More informationElectricity and Water Analogy
[ Assignment View ] [ Eðlisfræði 2, vor 2007 25. Current, Resistance, and Electromagnetic Force Assignment is due at 2:00am on Wednesday, February 14, 2007 Credit for problems submitted late will decrease
More informationHomework 5 chapter 28: 2, 7, 31, 43
http://iml.umkc.edu/physics/wrobel/phy5/homework.htm Homework 5 chapter 8:, 7, 3, 43 Problem 8. Two.5V batteries (with their positive terminals in the same direction) are inserted in series into the barrel
More informationChapter 11 Electricity
Chapter 11 Electricity Course Content Definition of Electricity Circuit Diagrams Series and Parallel Circuits Calculating total resistances Measurement of Electricity Ammeters and Voltmeters Ohm s Law
More informationSolutions to Bulb questions
Solutions to Bulb questions Note: We did some basic circuits with bulbs in fact three main ones I can think of I have summarized our results below. For the final exam, you must have an understanding of
More informationChapter 13: Electric Circuits
Chapter 13: Electric Circuits 1. A household circuit rated at 120 Volts is protected by a fuse rated at 15 amps. What is the maximum number of 100 watt light bulbs which can be lit simultaneously in parallel
More information1 of 11. Current Concept Tests.
1 of 11 Current Concept Tests. CRKT1. ote TRUE(A) if both statements below are always true. Otherwise, vote FALSE(B). For resistors in series, the current through each resistor is the same. For resistors
More informationSamples of conceptual and analytical/numerical questions from chap 20, C&J, 7E
Samples of conceptual and analytical/numerical questions from chap 0, C&J, 7E CHAPTE 0 CICUITS CONCEPTUAL QUESTIONS Cutnell & Johnson 7E. When an incandescent light bulb is turned on, the tungsten filament
More informationChapter 13 Electric Circuits
Chapter 13 Electric Circuits What is Electric Current? How does it resemble the flow of water in a pipe? Can you get a flashlight bulb to light, with a battery and a single wire? Electric Circuits and
More informationSample Exam #3 Electricity Physics 103 Spring 2011
Sample Exam #3 Electricity Physics 103 Spring 2011 1. An electric heater is constructed by applying a potential difference of 110 V across a wire with a resistance of 5.0 Ω. What is the power rating of
More informationCURRENT ELECTRICITY  I
CURRNT LCTRCTY  1. lectric Current 2. Conventional Current 3. Drift elocity of electrons and current 4. Current Density 5. Ohm s Law 6. Resistance, Resistivity, Conductance & Conductivity 7. Temperature
More information1. If each of the four resistors below has a resistance of 1 µω, what is the equivalent resistance of the combination?
1. If each of the four resistors below has a resistance of 1 µω, what is the equivalent resistance of the combination? V (a) 0.25 µω (b) 1 µω (c) 2 µω (d) 4 µω (e) none of these 2. Three identical lamps
More informationPhysics 1653 Exam 3  Review Questions
Physics 1653 Exam 3  Review Questions 3.0 Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a negatively charged rod is held near, but
More informationUnit 7: Electric Circuits
Multiple Choice Portion 1. The diagram below shows part of an electrical circuit. Unit 7: Electric Circuits 4. A 12 V battery supplies a 5.0 A current to two light bulbs as shown below. What are the magnitude
More informationChapter 28. DirectCurrent Circuits
Chapter 28. DirectCurrent Circuits esistors in Series and Parallel (gnore internal resistances for batteries in this section.) 281. A 5 resistor is connected in series with a 3 resistor and a 16V
More informationDC Circuits: Ch 19. Resistors in Series 6/1/2016
DC Circuits: Ch 19 Voltage Starts out at highest point at + end of battery Voltage drops across lightbulbs and other sources of resistance. Voltage increases again at battery. I The following circuit uses
More informationQ26.1 Which of the two arrangements shown has the smaller equivalent resistance between points a and b? A. the series arrangement B.
Q26.1 Which of the two arrangements shown has the smaller equivalent resistance between points a and b? A. the series arrangement B. the parallel arrangement C. The equivalent resistance is the same for
More informationHomework. Reading: Chap. 30, Chap. 31 and Chap. 32. Suggested exercises: 31.1, 5, 6, 7, 8, 13, 14, 17, 23, 24, 25
Homework Reading: Chap. 30, Chap. 31 and Chap. 32 Suggested exercises: 31.1, 5, 6, 7, 8, 13, 14, 17, 23, 24, 25 Problems: 31.35, 31.38, 31.41, 31.42, 31.49, 31.54, 31.57, 31.63, 31.64, 31.67, 31.70, 31.73
More informationEðlisfræði 2, vor 2007
[ Assignment View ] [ Pri Eðlisfræði 2, vor 2007 31. Alternating Current Circuits Assignment is due at 2:00am on Wednesday, March 21, 2007 Credit for problems submitted late will decrease to 0% after the
More informationPHYS2020: General Physics II Course Lecture Notes Section III
PHYS2020: General Physics Course Lecture Notes Section Dr. Donald G. Luttermoser East Tennessee State University Edition 4.0 Abstract These class notes are designed for use of the instructor and students
More informationCh. 20 Electric Circuits
Ch. 0 Electric Circuits 0. Electromotive Force Every electronic device depends on circuits. Electrical energy is transferred from a power source, such as a battery, to a device, say a light bulb. Conducting
More informationDC CIRCUITS. Responses to Questions
D UTS 19 esponses to Questions 1. Even though the bird s feet are at high potential with respect to the ground, there is very little potential difference between them, because they are close together on
More informationProblem Set 4 SOLUTION
University of Alabama Department of Physics and Astronomy PH 1022 / LeClair Spring 2008 Problem Set 4 SOLUTON 1. 10 points. An 11.0 W compact fluorescent bulb is designed to produce the same illumination
More informationCURRENT ELECTRICITY OHM S LAW KIRCHHOFF S LAW
CURRENT ELECTRICITY OHM S LAW KIRCHHOFF S LAW 1 01. A current of 16mA flows through a conductor. The number of electrons flowing per second is, (1) 10 14 (2) 10 15 (3) 1017 (4) 10 17 2 Solution (1):
More informationResistors in Series and Parallel
Resistors in Series and Parallel Bởi: OpenStaxCollege Most circuits have more than one component, called a resistor that limits the flow of charge in the circuit. A measure of this limit on charge flow
More informationResistance Review Following the potential around a circuit Multiloop Circuits RC Circuits
DC Circuits esistance eview Following the potential around a circuit Multiloop Circuits C Circuits Homework for today: ead Chapters 6, 7 Chapter 6 Questions, 3, 0 Chapter 6 Problems, 7, 35, 77 Homework
More informationElectric Current and Current Density. Ohm s Law: resistance and resistors
CH25: Current, Resistance and Electromotive Force Electric Current and Current Density Drift Velocity Resistivity Ohm s Law: resistance and resistors Circuits Connection and emf Energy and Power in Circuits
More informationEðlisfræði 2, vor 2007
[ Assignment View ] [ Print ] Eðlisfræði 2, vor 2007 30. Inductance Assignment is due at 2:00am on Wednesday, March 14, 2007 Credit for problems submitted late will decrease to 0% after the deadline has
More informationDirectCurrent Circuits
8 DirectCurrent Circuits Clicker Questions Question N.0 Description: Understanding circuits with parallel resistances. Question A battery is used to light a bulb as shown. A second bulb is connected by
More informationChapter 7. DC Circuits
Chapter 7 DC Circuits 7.1 Introduction... 73 Example 7.1.1: Junctions, branches and loops... 74 7.2 Electromotive Force... 75 7.3 Electrical Energy and Power... 79 7.4 Resistors in Series and in Parallel...
More informationMore Concepts. I = dq. Current is the rate of flow of charge around a circuit.
RC Circuits In this presentation, circuits with multiple batteries, resistors and capacitors will be reduced to an equivalent system with a single battery, a single resistor, and a single capacitor. Kirchoff's
More informationThe current that flows is determined by the potential difference across the conductor and the resistance of the conductor (Ohm s law): V = IR P = VI
PHYS1000 DC electric circuits 1 Electric circuits Electric current Charge can move freely in a conductor if an electric field is present; the moving charge is an electric current (SI unit is the ampere
More informationChapter 18 DirectCurrent Circuits
Chapter 8 DirectCurrent Circuits roblem Solutions 8. From r, the internal resistance is r 9.00 7.0 4.9 0.7 A 8. (a) When the three resistors are in series, the uivalent resistance of the circuit is 9.0
More informationChapter 23 Practice Problems, Review, and Assessment
Section 1 Simple Circuits: Practice Problems 1. Three 22Ω resistors are connected in series across a 125V generator. What is the equivalent resistance of the circuit? What is the current in the circuit?
More informationChapter 23 Circuits. Reading Quiz. Answer. Reading Quiz. Topics: Sample question:
Chapter 23 Circuits Topics: Circuits containing multiple elements Series and parallel combinations RC circuits Electricity in the nervous system Reading Quiz 1. The bulbs in the circuit below are connected.
More informationRC Circuits. Honors Physics Note 002 c Alex R. Dzierba Honors Physics P222  Spring, 2004
R ircuits Honors Physics Note 2 c Alex R. Dziera Honors Physics P222  Spring, 24 Introduction This note concerns the ehavior of circuits that include cominations of resistors, capacitors and possily a
More informationTime dependent circuits  The RC circuit
Time dependent circuits  The circuit Example 1 Charging a Capacitor Up until now we have assumed that the emfs and resistances are constant in time, so that all potentials, currents and powers are constant
More informationProblem Solving 8: RC and LR Circuits
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics Problem Solving 8: RC and LR Circuits Section Table and Group (e.g. L04 3C ) Names Hand in one copy per group at the end of the Friday Problem
More informationChapter 17 Study Questions Name: Class:
Chapter 17 Study Questions Name: Class: Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. If two charges repel each other, the two charges
More informationChapter 27 = J. U = 120Ah 3600s 1h. Now we compute how long we can deliver a power of 100 W with this energy available.
Chapter 7 7. A certain car battery with 1.0 V emf has an initial carge of 10 A h. Assuming that the potential across the terminals stays constant until the battery is completely discharged, for how many
More informationProfs. A. Petkova, A. Rinzler, S. Hershfield. Exam 2 Solution
PHY2049 Fall 2009 Profs. A. Petkova, A. Rinzler, S. Hershfield Exam 2 Solution 1. Three capacitor networks labeled A, B & C are shown in the figure with the individual capacitor values labeled (all units
More informationS15Physics current and Circuit PRACTICE
Name: Class: Date: ID: A S5Physics current and Circuit PRACTICE Multiple Choice Identify the choice that best completes the statement or answers the question.. Three resistors, with values of 2.0, 4.0
More informationObjectives 200 CHAPTER 4 RESISTANCE
Objectives Explain the differences among conductors, insulators, and semiconductors. Define electrical resistance. Solve problems using resistance, voltage, and current. Describe a material that obeys
More informationStudent Exploration: Circuits
Name: Date: Student Exploration: Circuits Vocabulary: ammeter, circuit, current, ohmmeter, Ohm s law, parallel circuit, resistance, resistor, series circuit, voltage Prior Knowledge Questions (Do these
More informationLecture 37. Power. Circuits. Parallel and Series Resistances. Cutnell+Johnson: Circuits
Lecture 37 Power Circuits Parallel and Series Resistances Cutnell+Johnson: 0.40.8 Circuits Now that we know about voltages, currents and resistance, we can talk about circuits. A circuit is simply a closed
More informationExam 2 Solutions. PHY2054 Spring Prof. P. Kumar Prof. P. Avery March 5, 2008
Prof. P. Kumar Prof. P. Avery March 5, 008 Exam Solutions 1. Two cylindrical resistors are made of the same material and have the same resistance. The resistors, R 1 and R, have different radii, r 1 and
More informationChapter 6. Experiment 4: Electric Currents and Circuits. 6.1 Introduction The Electric Current
Chapter 6 Experiment 4: Electric Currents and Circuits 6.1 Introduction The resistance to the flow of an electric current is essential in the design of electronic devices and electric circuits generally.
More informationClicker Question. Which of the two arrangements shown has the smaller equivalent resistance between points a and b?
Which of the two arrangements shown has the smaller equivalent resistance between points a and b? A. the series arrangement B. the parallel arrangement C. The equivalent resistance is the same for both
More informationResistors in Series. Section 28.2
esistors in Series When two or more resistors are connected endtoend, they are said to be in series. For a series combination of resistors, the currents are the same in all the resistors because the amount
More informationObjectives. to understand how to use a voltmeter to measure voltage
UNIT 10 MEASUREMENTS OF VOLTAGE (from Lillian C. McDermott and the Physics Education Group, Physics by Inquiry Volume II, John Wiley and Sons, NY, 1996) Objectives to understand how to use a voltmeter
More informationElectric Circuits II. Physics 133 Experiments Electric Circuits II 1
Physics 133 Experiments Electric Circuits II 1 Electric Circuits II GOALS To examine Ohm's Law: the pivotal relationship between voltage and current for resistors To closely study what current does when
More informationPhysics 2212 GH Quiz #4 Solutions Spring 2015
Physics 1 GH Quiz #4 Solutions Spring 15 Fundamental Charge e = 1.6 1 19 C Mass of an Electron m e = 9.19 1 31 kg Coulomb constant K = 8.988 1 9 N m /C Vacuum Permittivity ϵ = 8.854 1 1 C /N m Earth s
More informationKirchhoff s Voltage Law and RC Circuits
Kirchhoff s oltage Law and RC Circuits Apparatus 2 1.5 batteries 2 battery holders DC Power Supply 1 multimeter 1 capacitance meter 2 voltage probes 1 long bulb and 1 round bulb 2 sockets 1 set of alligator
More informationCHAPTER 19: DC Circuits. Answers to Questions
HAPT 9: D ircuits Answers to Questions. The birds are safe because they are not grounded. Both of their legs are essentially at the same voltage (the only difference being due to the small resistance of
More informationHomework #11 20311721 Physics 2 for Students of Mechanical Engineering
Homework #11 20311721 Physics 2 for Students of Mechanical Engineering 2. A circular coil has a 10.3 cm radius and consists of 34 closely wound turns of wire. An externally produced magnetic field of
More informationChapter 21 Electric Current and DirectCurrent Circuit
Chapter 2 Electric Current and DirectCurrent Circuit Outline 2 Electric Current 22 Resistance and Ohm s Law 23 Energy and Power in Electric Circuit 24 Resistance in Series and Parallel 25 Kirchhoff
More informationDC Circuits. 3. Three 8.0 resistors are connected in series. What is their equivalent resistance? a c b. 8.0 d. 0.13
DC Circuits 1. The two ends of a 3.0 resistor are connected to a 9.0V battery. What is the current through the resistor? a. 27 A c. 3.0 A b. 6.3 A d. 0.33 A 2. The two ends of a 3.0 resistor are connected
More informationChapter 25 Electric Current and DirectCurrent Circuits
hapter 5 Electric urrent and Directurrent ircuits Formatted onceptual Problems heater consists of a variable resistor (a resistor whose resistance can be varied) connected across an ideal voltage supply.
More informationQuestion Bank. Electric Circuits, Resistance and Ohm s Law
Electric Circuits, Resistance and Ohm s Law. Define the term current and state its SI unit. Ans. The rate of flow of charge in an electric circuit is called current. Its SI unit is ampere. 2. (a) Define
More information7. What is the current in a circuit if 15 coulombs of electric charge move past a given point in 3 seconds? (1) 5 A (3) 18 A (2) 12 A (4) 45 A
1. Compared to the number of free electrons in a conductor, the number of free electrons in an insulator of the same volume is less the same greater 2. Most metals are good electrical conductors because
More informationCurrent, Resistance and Electromotive Force. Young and Freedman Chapter 25
Current, Resistance and Electromotive Force Young and Freedman Chapter 25 Electric Current: Analogy, water flowing in a pipe H 2 0 gallons/minute Flow Rate is the NET amount of water passing through a
More informationUniversity Physics 227N/232N Current and Ohm s Law, Resistors, Circuits, and Kirchoff Lab this Friday, Feb 28 So NO QUIZ this Friday!
University Physics 227N/232N Current and Ohm s Law, Resistors, Circuits, and Kirchoff Lab this Friday, Feb 28 So NO QUIZ this Friday! Dr. Todd Satogata (ODU/Jefferson Lab) and Fred Miller satogata@jlab.org
More informationElectricity ReviewSheet
Name: ate: 1. The unit of electrical charge in the MKS system is the. volt. ampere. coulomb. mho 2. Which sketch best represents the charge distribution around a neutral electroscope when a positively
More information2 A bank account for electricity II: flows and taxes
PHYS 189 Lecture problems outline Feb 3, 2014 Resistors and Circuits Having introduced capacitors, we now expand our focus to another very important component of a circuit resistors. This entails more
More informationLecture 11. Kirchoff Circuit Rules RC Circuits
Lecture 11 Kirchoff ircuit ules  ircuits 1 V 1 1 eview 2 V 2 2 n this circuit, assume V i and i are known. 3 V 3 3 What is 2?? We have the following 4 equations: 1. 2 = 1 + 3 2.  V 1 + 1 13 3 + V 3
More informationFigure 1. Experiment 3 The students construct the circuit shown in Figure 2.
Series and Parallel Circuits When two or more devices are connected to a battery in a circuit, there are a couple of methods by which they can be connected. One method is called a series connection and
More informationPhys 102 Spg Exam No. 2 Solutions
Phys 102 Spg. 2008 Exam No. 2 Solutions I. (20 pts) A 10turn wire loop measuring 8.0 cm by 16.0 cm carrying a current of 2.0 A lies in the horizontal plane and is free to rotate about a horizontal axis
More informationChapter 18: Circuits and Circuit Elements 1. Schematic diagram: diagram that depicts the construction of an electrical apparatus
Chapter 18: Circuits and Circuit Elements 1 Section 1: Schematic Diagrams and Circuits Schematic Diagrams Schematic diagram: diagram that depicts the construction of an electrical apparatus Uses symbols
More informationR=ρL/A ρ is the resistivity, and depends on the material used ρ reflects intrinsic properties of the material ρ is a function of temperature
Factors that govern Material ρ The ability to carry electric current varies drastically Length L The longer the conductor, the greater its resistance Cross sectional area A The thicker the conductor, the
More information