1. Cutnell/Johnson Physics 8th edition Reading Quiz Questions
Classroom Response System Questions
Chapter 20 Electric Circuits
Reading Quiz Questions

2. The positive terminal of a battery in a minivan has an electric potential that is a maximum of 12 V higher than the negative terminal. Complete the following sentence: When wires are connected to the battery from the various electrical circuits within the minivan, the potential difference between the two terminals is
a) equal to 12 V.
b) less than 12 V.
c) greater than 12 V.
d) equal to zero V.

3. 20.1.2. Which one of the following units are the correct SI units for the electromotive force (emf)?
a) newtons (N)
b) coulombs (C)
c) joules (J)
d) amperes (A)
e) volts (V)

4. 20.1.3. Which one of the following statements concerning the conventional current is true?
a) The conventional current is the hypothetical movement of positive charges through the wires of an electric circuit.
b) The conventional current is the movement of electrons through the wires of an electric circuit.
c) The conventional current is equal to the electromotive force of the battery in an electric circuit.
d) The conventional current always moves clockwise around a circuit.
e) The conventional current is the one that moves in a dc circuit and an
unconventional current is one that moves in an ac circuit.

5. Through a certain cross-sectional area of a wire, one coulomb of electrons pass each second. In this case, the current through the wire is equal to which one of the following choices?
a) one electron volt
b) one volt
c) one ampere
d) one watt
e) one joule per second

6. Which one of the following statements concerning the electric field in an electric circuit containing a long wire attached across the terminals of a battery is false?
a) The direction of the electric field is parallel to the wires that form the circuit.
b) The electric field exerts a force on free electrons within the wire.
c) The electric field is directed from the positive terminal toward the negative terminal.
d) The electric field lies only within a thin region near the surface of the wires.
e) The electric field within the wire makes the electric current possible.

7. 20. 1. 6. The unit of electrical current is the ampere (A)
The unit of electrical current is the ampere (A). Which one of the combinations of units is equivalent to the ampere?
a) C  s
b) C/s
c) N  m/s
d) J  s
e) kg  m2/s

8. 20.1.7. How is the direction of current flow defined in a conductor?
a) It is in the direction of the force on a charged particle.
b) It is in the direction that the atoms move.
c) It is in the direction that positively-charged particles would move.
d) It is in the direction that positively-charged particles would move.
e) It is up to the person doing a given problem to decide the direction.

9. 20.2.1. Which one of the following statements related to Ohm’s law is false?
a) The ratio of the voltage applied across a wire to the current flowing through it is constant.
b) Resistance is expressed in ohms.
c) Georg Simon Ohm discovered the law named after him.
d) The resistance of all materials falls within a narrow range of values between 1 and 100 .
e) One ohm is equal to one volt divided by one ampere.

10. 20.2.2. In most cases, Ohm’s law is valid when which of the following conditions is satisfied?
a) when, for a given piece of material, the ratio V/I is the same for a wide range of voltages and currents
b) when there is a direct current passing through a given piece of material
c) when the voltage across a piece of material is constant for a wide range of currents
d) when the current through a piece of material is constant for a wide range of voltages
e) when the voltage decreases with increasing current through a piece of material

11. 20.2.3. By which of the following methods could the current in a given circuit be doubled?
a) Either double the resistance or double the voltage.
b) Reduce either the voltage or the resistance to half of the initial value.
c) Either double the voltage or reduce the resistance to half of its initial value.
d) Either double the resistance or reduce the voltage to half of its initial value.
e) None of the above answers are correct.

12. 20.3.1. Complete the following sentence: the electrical resistivity of most metal wires is
a) constant, even when the temperature of the metals varies greatly.
b) independent of the length of the wire.
c) expressed in ohms.
d) much smaller than the values for most semiconductors.
e) inversely proportional to the cross-sectional area of the wire.

13. In the fabrication of an electrical extension cord, the manufacturer wants to reduce the overall resistance of the wires in the extension cord. Which of the following changes would result in the lowest resistance?
a) decrease the diameter of the wires
b) increase the diameter of the wires
c) choose a metal wire with a larger value of resistivity
d) increase the length of the extension cord
e) choose a metal with a larger value for the temperature coefficient of resistivity

14. 20.3.3. Which one of the following types of materials exhibits the largest values of resistivity?
a) insulators
b) semiconductors
c) semimetals
d) metals

15. Which pair of terms correctly fills the blanks in the following sentence? ________ is a property of an object while ________ is a property of a material.
a) resistivity, conductivity
b) current, current density
c) current, resistance
d) resistance, current
e) resistance, resistivity

16. 20.4.1. Complete the following sentence: The SI unit for electric power is
a) kilowatt-hour.
b) light-year.
c) watt.
d) joule.
e) farad.

17. Which one of the following equations is not a valid expression for electric power P? Note: I is the current in a circuit as a result of a voltage V and R is the electrical resistance of the circuit.
a) P = I2R
b) P =
c) P = IV
d) P =

18. What kind of materials exhibit zero resistivity when the temperature is reduced below a critical temperature for that material?
a) semiconductors
b) piezoelectrics
c) ferroelectrics
d) perovskites
e) superconductors

19. 20. 4. 4. The SI unit of power is the watt
The SI unit of power is the watt. Which of the following units are equivalent to the watt?
a) V∙A
b) J/C
c) C/s
d) V/s
e) A/s

20. The type of current that flows through a refrigerator when it is plugged into a wall socket is which of the following?
a) alternating
b) direct
c) ambulatory
d) endless
e) magnetic

21. In an ac circuit containing a generator and a resistance, the voltage fluctuates in a sinusoidal manner. How does the current in such a circuit behave?
a) The current has a constant value with time.
b) The current also varies in a similar sinusoidal manner.
c) The current alternates, but it only has two values with time, +I and I.
d) Since electrons do not flow in such a circuit, the current is zero amperes.

22. Which of the following actions would significantly reduce the risk of fire when using an electric heater connected to a wall outlet using an extension cord?
a) use a longer extension cord
b) use an extension cord with larger-gauge wires
c) use a shorter extension cord
d) use an extension cord with smaller-gauge wires
e) use an extension cord with three prongs on the end rather than two

23. Two identical resistors are connected in series across the terminals of an ideal battery with a voltage V and a current I flows through the circuit. If one of the resistors is removed from the circuit and the remaining one connected across the terminals of the battery, how much current would flow through the circuit?
a) 4I
b) 2I
c) I
d) I/2
e) I/4

24. One end of resistor A is connected to the positive terminal of a battery and the other end is connected to resistor B. The opposite end of resistor B is connected to the negative terminal of the battery. If resistor A has resistance R and B has a resistance 2R, what is the equivalent resistance of this circuit?
a) R
b) 3R/2
c) 2R
d) 2R/3
e) 3R

25. 20.7.1. Which of the following statements concerning resistors that are wired in parallel is true?
a) The current through each resistor is necessarily the same.
b) The equivalent resistance for the resistors in the circuit is the sum of the individual resistances.
c) The voltage across each resistor is necessarily the same.
d) The equivalent resistance for the resistors in the circuit is the product of the individual resistances.
e) The equivalent resistance for the resistors in the circuit is the average of the individual resistances.

26. A television, satellite receiver, and a DVD player are plugged into the same wall electrical outlet at Nancy’s house. Which of the following statements concerning this situation is false when these appliances are being used?
a) The same voltage is provided to each of the three appliances by the outlet.
b) Each appliance draws the same current as it would if the other two devices were not plugged into the outlet.
c) The equivalent resistance of the three devices is less than the sum of the
individual resistances.
d) The current drawn by each of the three devices is identical.
e) Each appliance dissipates the same average power as it would if the other two devices were not plugged into the outlet.

27. Two resistors can be either connected to a battery in series or in parallel. In which case, if either, is the equivalent resistance the smallest?
a) When the two resistors are wired in parallel, the equivalent resistance is less than if they are wired in series.
b) When the two resistors are wired in series, the equivalent resistance is less than if they are wired in parallel.
c) Both series and parallel wiring will result in the same equivalent resistance.
d) It is not possible to know which method of wiring will result in the lowest equivalent resistance without knowing the values of the two resistances.

28. In analyzing circuits in which resistors are wired partially in series and partially in parallel, which one of the following statements describes the preferred approach to take to determine the equivalent resistance in the circuit?
a) Find the sum of all the resistors. This is the equivalent resistance for the circuit.
b) Break the circuit into smaller parts and find an equivalent resistance for each part. Then continue this process until all of the parts are added together correctly either in series or parallel until a single equivalent resistance is found.
c) All together all of the resistors in series, ignoring any wired in parallel as they do not significantly add to the equivalent resistance of the circuit. The sum of the resistors in series is the equivalent resistance.
d) All together all of the resistors in parallel, ignoring any wired in series as they do not significantly add to the equivalent resistance of the circuit. The sum of the resistors in parallel is the equivalent resistance.

29. Which one of the following terms describes the resistance that a battery or a generator has in a circuit?
a) super resistance
b) critical resistance
c) internal resistance
d) terminal resistance
e) electroresistance

30. 20.10.1. Which one of the following choices is not one of Kirchoff’s rules?
a) junction rule
b) slide rule
c) loop rule

31. Complete the following statement: The sum of the magnitudes of the currents directed into a junction
a) is divided equally among the number of lines directed out of the junction.
b) is less than the total current directed out of the junction.
c) equals the current that is directed along one of the lines out of the junction.
d) equals the sum of the magnitudes of the currents directed out of the junction.
e) is greater than the total current directed out of the junction.

32. Complete the following statement: Around any closed-circuit loop, the sum of the potential drops
a) dramatically with the addition of each resistor.
b) in each loop is the same.
c) equals the sum of the potential rises.
d) equals the emf of the battery.
e) increases with the addition of each resistor.

33. In analyzing electric circuits containing a battery and at least one resistor, what is the change in potential across a resistor as one moves through it in the direction of the current?
a) +i2R
b) i2R
c) +iR
d) iR
e) zero

34. One end of resistor A is connected to the positive terminal of a battery and the other end is connected to resistor B. The opposite end of resistor B is connected to the negative terminal of the battery. If resistor A has resistance R and B has a resistance 2R, what is the equivalent resistance of this circuit?
a) R
b) 3R/2
c) 2R
d) 2R/3
e) 3R

35. While analyzing the currents within a circuit containing multiple components (such as batteries, resistors, etc.), which of the following statements concerning currents flowing into a single junction must be true?
a) The sum of the currents entering the junction must equal the total current through the battery.
b) The sum of the currents entering the junction must equal zero.
c) The sum of the currents entering the junction must equal the sum of the currents exiting the junction.
d) The currents entering the junction must follow only one of the possible exit paths.
e) The currents entering the junction may exit back along the path from which they entered.

36. The fact that the sum of the currents entering any junction in an electric circuit must be equal to the sum of the currents leaving the junction is an expression of what principle?
a) conservation of energy
b) Heisenberg uncertainty principle
c) conservation of momentum
d) Archimedes' Principle
e) conservation of charge

37. Which of the following devices is used placed into a circuit to measure the current that passes through it?
a) ammeter
b) gaussmeter
c) voltmeter
d) diffractometer
e) flowmeter

38. 20.11.2. Which one of the following statements is not a characteristic of a voltmeter?
a) The voltmeter measures the voltage between two points in a circuit.
b) The voltmeter is designed to measure nearly the same voltage that is present when the meter is not connected.
c) The voltmeter is not placed directly into a circuit.
d) The voltmeter is designed to draw very little current from the circuit being measured.
e) An ideal voltmeter has almost no resistance.

39. 20. 12. 1. Three capacitors are connected in parallel to a battery
Three capacitors are connected in parallel to a battery. How is the equivalent capacitance for this circuit determined?
a) The equivalent capacitance is the sum of the three capacitances.
b) The equivalent capacitance is the sum of the three capacitances divided by three. In other words, the equivalent capacitance is the average capacitance in the circuit.
c) The potential drop across each capacitor is measured and multiplied by each capacitance before adding them together.
d) A resistor is used to replace one capacitor at a time. Then, the current through the resistor is measured and used to determine the charge on each capacitor. The sum of the charges is then divided by the emf of the battery to find the equivalent capacitance.
e) Unlike resistors, an equivalent capacitance cannot be found by any simple means.

40. 20. 12. 2. Three capacitors are connected in series to a battery
Three capacitors are connected in series to a battery. Which one of the following statements concerning this situation is true?
a) The amount of charge on each capacitor depends on its capacitance. If the capacitors have different capacitances, they will have differing amounts of charge on their plates.
b) The equivalent capacitance is less than the sum of the individual capacitances.
c) The battery must move more charge when the capacitors are connected in series than when connected in parallel.
d) An equivalent capacitance can be found for capacitors connected in series, but not when they are connected in parallel.
e) The equivalent capacitance is equal to the sum of the individual capacitances.

41. How does the capacitance of two identical capacitors connected in parallel compare to that of one of the capacitors?
a) The two capacitors connected in series have a larger capacitance.
b) The two capacitors connected in series have the same capacitance.
c) The two capacitors connected in series have a smaller capacitance.

42. How does the capacitance of two identical capacitors connected in series compare to that of one of the capacitors?
a) The two capacitors connected in series have a larger capacitance.
b) The two capacitors connected in series have the same capacitance.
c) The two capacitors connected in series have a smaller capacitance.

43. 20. 13. 1. Consider each of the graphs shown
Consider each of the graphs shown. Which of these graphs represents the charge on a capacitor as it is being charged in a circuit containing a resistor and a capacitor in series shortly after they are connected to a battery?
a) A
b) B
c) C
d) D
e) E

44. A circuit contains a capacitor with a capacitance C and a resistor with a resistance R connected in series with a battery. Which one of the following mathematical expressions correctly represents the time constant for this circuit? a) b) c) d) e)

45. 20.13.3. When does a charging capacitor stop charging?
a) when the amount of charge on the two plates is equal
b) when the potential difference across the plates of the capacitor is equal to zero volts
c) when the amount of charge on the two plates is infinitely large
d) when the potential difference across the plates of the capacitor is equal to the emf of the battery
e) when all of the charge available in the circuit has been forced to collect on the plates of the capacitor

46. 20.13.4. Which of the following quantities is equal to the time constant for a charging capacitor?
a) the time it takes a capacitor to reach 37 % of its maximum charge
b) the time it takes a capacitor to reach 50 % of its maximum charge
c) the time it takes a capacitor to reach 63 % of its maximum charge
d) the time it takes a capacitor to reach 75 % of its maximum charge
e) the time it takes a capacitor to reach its maximum charge

47. What effect, if any, does increasing the capacitance in an RC circuit have on the charging of the capacitor?
a) The capacitance has no effect on the charging of the capacitor, which is determined by the emf of the battery and the circuit resistance.
b) Increasing the capacitance causes the charging time to increase since the rate at which charges are moving to the capacitor increases.
c) The charging time will decrease as the capacitance is increased because the rate at which charges are moving to the capacitor decreases.
d) Increasing the capacitance increases the charging time since the capacitor can hold more charge.
e) Increasing the capacitance decreases the charging time since the emf of the battery will be reduced.