Question 1

Which of the following statements is false?

Accepted Answer

A)  An electric field is needed to produce an electric current. 
B)  A potential difference between two points is needed to produce an electric current. 
C)  For a steady current to flow in a wire, the wire must be part of a closed circuit. 
D)  The electric field is constant along all parts of the circuit when a steady current is flowing. 
E)  The electric current in a wire is proportional to the drift velocity of the charges.

Question 2

The current in the 2-$\Omega$ resistor is 2 A. What is the potential difference across the 3-$\Omega$ resistor?

Accepted Answer

A)  4 V 
B)  6 V 
C)  2 V 
D)  8 V 
E)  None of these is correct.

Question 3

In a laboratory experiment, two unequal resistors are connected individually, then in series, and then in parallel to a group of batteries. Four sets of observations are made of the potential differences and the corresponding total currents and curves are plotted as shown. The curve that represents the smaller of the two resistors is

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  None of these is correct.

Question 4

The resistivity of any given metal

Accepted Answer

A)  depends on its temperature. 
B)  varies linearly with temperature. 
C)  is the proportionality constant between the resistance, R, and the ratio of the length, L, to the cross-sectional area, A, of a wire made of the metal. 
D)  has units of ohm-meter. 
E)  is described by all of the above.

Question 5

When the ammeter  reads 7 A, the voltmeter  reads

Accepted Answer

A)  2.8 V with Y at the higher potential. 
B)  2.8 V with X at the higher potential. 
C)  34 V with Y at the higher potential. 
D)  34 V with X at the higher potential. 
E)  60 V with X at the higher potential.

Question 6

In the above circuit, $\varepsilon$1 = 9 V, $\varepsilon$2 = 6 V, and $\varepsilon$3 = 6 V. Also R1 = 25 $\Omega$, R2 = 125 $\Omega$, and R3 = 55$\Omega$. Find the current flowing through R3.

Accepted Answer

A)  0.60 A 
B)  0.072 A 
C)  0.68 A 
D)  0.36 A 
E)  0.020 A

Question 7

Capacitors C1 and C2 are connected in series to the battery as shown. When you close switch S, a momentary current is indicated by

Accepted Answer

A)  ammeter A1 only. 
B)  ammeter A2 only. 
C)  ammeter A3 only. 
D)  ammeter A1 and A3 only. 
E)  all of the ammeters.

Question 8

You want to use a metal bar as a resistor. Its dimensions are 2 by 4 by 10 units. To get the smallest resistance from this bar, you should attach leads to the two opposite sides that have the dimensions of

Accepted Answer

A)  2 by 4 units. 
B)  2 by 10 units. 
C)  4 by 10 units. 
D)  any number of units because all connections give the same resistance. 
E)  None of these is correct.

Question 9

A sensitive galvanometer has a resistance of 180 $\Omega$ and requires 2.40$\mu$A of current to produce a full-scale deflection. The series resistance needed to construct a voltmeter that gives full-scale deflection for a potential difference of 10.0 V is approximately

Accepted Answer

A)  4.17 M$\Omega$ 
B)  180 $\Omega$ 
C)  1.80 k$\Omega$ 
D)  8.33 M$\Omega$ 
E)  2.08 M$\Omega$

Question 10

By what percentage does the resistance of a copper wire ($\alpha$ = 3.9 *10-3/K) increase when its temperature increases from 20 to 75ºC?

Accepted Answer

A)  11% 
B)  14% 
C)  22% 
D)  31% 
E)  57%

Question 11

You connect two identical resistors in series across supply lines maintained at a constant potential difference. When you later connect them in parallel across the same supply lines, the total current furnished by the supply lines, compared with the former current, is

Accepted Answer

A)  exactly the same. 
B)  twice as great. 
C)  one-half as much. 
D)  four times as great. 
E)  one-fourth as much.

Question 12

The current through and the potential difference across a black box  is measured by which of the given ammeter  and voltmeter  configurations?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 13

An energy efficient light bulb uses 15 W of power for an equivalent light output of a
60 W incandescent light bulb. How much energy is saved each month by using the energy efficient light bulb instead of the incandescent light bulb for 4 hours a day? Assume that there are 30 days in one month.

Accepted Answer

A)  5.4 kW.hr 
B)  1.35 kW.hr 
C)  21.6 kW.hr 
D)  1.8 kW.hr 
E)  7.2 kW.hr

Question 14

Use the diagram for the next two problems: 
-The switch S is initially at position b for a long time. It is then switched to position a. Describe what happens to the light bulb as a function of time when the switch is flipped from b to a?

Accepted Answer

A)  The light bulb was on but goes off immediately. 
B)  The light bulb was off and stays off. 
C)  The light bulb was on but its brightness decreases with time and eventually goes off. 
D)  The light bulb was on and stays on. 
E)  The light bulb was off. It then lights up but the brightness decreases with time and eventually goes off.

Question 15

The power delivered by the battery in the circuit shown is

Accepted Answer

A)  2.5 W 
B)  7.0 W 
C)  3.1 W 
D)  9.7 W 
E)  5.3 W

Question 16

Four identical light bulbs are connected to a power supply as shown. Which light bulb consumes the most power?

Accepted Answer

A)  B1 
B)  B2 
C)  B3 
D)  B4 
E)  B2, B3, and B4

Question 17

Doubling the capacitance in an RC circuit

Accepted Answer

A)  doubles the time constant of the circuit. 
B)  halves the time constant of the circuit. 
C)  has no effect on the time constant of the circuit. 
D)  has no effect on the rate at which energy is dissipated by the circuit. 
E)  None of these is correct.

Question 18

An electric generator supplies power as a function of time according to the expression
P(t) = 2t + 3t2
Where the units are SI. The electric energy provided by the generator between t = 0 and t = 1 s is

Accepted Answer

A)  1.8 J 
B)  2.0 J 
C)  2.5 J 
D)  5.0 J 
E)  8.0 J

Question 19

A heating element made of nichrome wire (temperature coefficient of resistivity,
$\alpha$ = 0.400 *10-3 K-1) is connected to a source. When it has just been turned on and its temperature is 20ºC, it dissipates 960 W of power. What power is dissipated when its temperature has risen to 300ºC?

Accepted Answer

A)  1.1* 103 W 
B)  9.6 *102 W 
C)  8.6 * 102 W 
D)  8.6 * 103 W 
E)  1.1 *102 W

Question 20

By what percentage does the resistance of a copper wire ($\alpha$ = 3.9 *10-3/K) increase when its temperature increases from 20ºC to 100ºC?

Accepted Answer

A)  11% 
B)  14% 
C)  23% 
D)  31% 
E)  57%

Exam 5: Electric Current and Direct-Current Circuits

Which of the following statements is false?

$The current in the 2- \Omega resistor is 2 A. What is the potential difference across the 3- \Omega resistor? A) 4 V B) 6 V C) 2 V D) 8 V E) None of these is correct.$ The current in the 2- $\Omega$ resistor is 2 A. What is the potential difference across the 3- $\Omega$ resistor?

The resistivity of any given metal

When the ammeter reads 7 A, the voltmeter reads

Capacitors C₁ and C₂ are connected in series to the battery as shown. When you close switch S, a momentary current is indicated by

You want to use a metal bar as a resistor. Its dimensions are 2 by 4 by 10 units. To get the smallest resistance from this bar, you should attach leads to the two opposite sides that have the dimensions of

A sensitive galvanometer has a resistance of 180 $\Omega$ and requires 2.40 $\mu$ A of current to produce a full-scale deflection. The series resistance needed to construct a voltmeter that gives full-scale deflection for a potential difference of 10.0 V is approximately

By what percentage does the resistance of a copper wire ( $\alpha$ = 3.9 *10^-3/K) increase when its temperature increases from 20 to 75ºC?

You connect two identical resistors in series across supply lines maintained at a constant potential difference. When you later connect them in parallel across the same supply lines, the total current furnished by the supply lines, compared with the former current, is

The current through and the potential difference across a black box is measured by which of the given ammeter and voltmeter configurations?

An energy efficient light bulb uses 15 W of power for an equivalent light output of a 60 W incandescent light bulb. How much energy is saved each month by using the energy efficient light bulb instead of the incandescent light bulb for 4 hours a day? Assume that there are 30 days in one month.

Use the diagram for the next two problems: -The switch S is initially at position b for a long time. It is then switched to position a. Describe what happens to the light bulb as a function of time when the switch is flipped from b to a?

The power delivered by the battery in the circuit shown is

Four identical light bulbs are connected to a power supply as shown. Which light bulb consumes the most power?

Doubling the capacitance in an RC circuit

An electric generator supplies power as a function of time according to the expression P(t) = 2t + 3t² Where the units are SI. The electric energy provided by the generator between t = 0 and t = 1 s is

A heating element made of nichrome wire (temperature coefficient of resistivity, $\alpha$ = 0.400 *10^-3 K^-1) is connected to a source. When it has just been turned on and its temperature is 20ºC, it dissipates 960 W of power. What power is dissipated when its temperature has risen to 300ºC?

By what percentage does the resistance of a copper wire ( $\alpha$ = 3.9 *10^-3/K) increase when its temperature increases from 20ºC to 100ºC?

Exam 5: Electric Current and Direct-Current Circuits

Which of the following statements is false?

The current in the 2- Ω\OmegaΩ resistor is 2 A. What is the potential difference across the 3- Ω\OmegaΩ resistor?

The resistivity of any given metal

When the ammeter reads 7 A, the voltmeter reads

In the above circuit, ε\varepsilonε 1 = 9 V, ε\varepsilonε 2 = 6 V, and ε\varepsilonε 3 = 6 V. Also R1 = 25 Ω\OmegaΩ , R2 = 125 Ω\OmegaΩ , and R3 = 55 Ω\OmegaΩ . Find the current flowing through R3.

Capacitors C1 and C2 are connected in series to the battery as shown. When you close switch S, a momentary current is indicated by

You want to use a metal bar as a resistor. Its dimensions are 2 by 4 by 10 units. To get the smallest resistance from this bar, you should attach leads to the two opposite sides that have the dimensions of

A sensitive galvanometer has a resistance of 180 Ω\OmegaΩ and requires 2.40 μ\muμ A of current to produce a full-scale deflection. The series resistance needed to construct a voltmeter that gives full-scale deflection for a potential difference of 10.0 V is approximately

By what percentage does the resistance of a copper wire ( α\alphaα = 3.9 *10-3/K) increase when its temperature increases from 20 to 75ºC?

You connect two identical resistors in series across supply lines maintained at a constant potential difference. When you later connect them in parallel across the same supply lines, the total current furnished by the supply lines, compared with the former current, is

The current through and the potential difference across a black box is measured by which of the given ammeter and voltmeter configurations?

An energy efficient light bulb uses 15 W of power for an equivalent light output of a 60 W incandescent light bulb. How much energy is saved each month by using the energy efficient light bulb instead of the incandescent light bulb for 4 hours a day? Assume that there are 30 days in one month.

Use the diagram for the next two problems: -The switch S is initially at position b for a long time. It is then switched to position a. Describe what happens to the light bulb as a function of time when the switch is flipped from b to a?

The power delivered by the battery in the circuit shown is

Four identical light bulbs are connected to a power supply as shown. Which light bulb consumes the most power?

Doubling the capacitance in an RC circuit

An electric generator supplies power as a function of time according to the expression P(t) = 2t + 3t2 Where the units are SI. The electric energy provided by the generator between t = 0 and t = 1 s is

A heating element made of nichrome wire (temperature coefficient of resistivity, α\alphaα = 0.400 *10-3 K-1) is connected to a source. When it has just been turned on and its temperature is 20ºC, it dissipates 960 W of power. What power is dissipated when its temperature has risen to 300ºC?

By what percentage does the resistance of a copper wire ( α\alphaα = 3.9 *10-3/K) increase when its temperature increases from 20ºC to 100ºC?

$The current in the 2- \Omega resistor is 2 A. What is the potential difference across the 3- \Omega resistor? A) 4 V B) 6 V C) 2 V D) 8 V E) None of these is correct.$ The current in the 2- $\Omega$ resistor is 2 A. What is the potential difference across the 3- $\Omega$ resistor?

Capacitors C₁ and C₂ are connected in series to the battery as shown. When you close switch S, a momentary current is indicated by

A sensitive galvanometer has a resistance of 180 $\Omega$ and requires 2.40 $\mu$ A of current to produce a full-scale deflection. The series resistance needed to construct a voltmeter that gives full-scale deflection for a potential difference of 10.0 V is approximately

By what percentage does the resistance of a copper wire ( $\alpha$ = 3.9 *10^-3/K) increase when its temperature increases from 20 to 75ºC?

An electric generator supplies power as a function of time according to the expression P(t) = 2t + 3t² Where the units are SI. The electric energy provided by the generator between t = 0 and t = 1 s is

A heating element made of nichrome wire (temperature coefficient of resistivity, $\alpha$ = 0.400 *10^-3 K^-1) is connected to a source. When it has just been turned on and its temperature is 20ºC, it dissipates 960 W of power. What power is dissipated when its temperature has risen to 300ºC?

By what percentage does the resistance of a copper wire ( $\alpha$ = 3.9 *10^-3/K) increase when its temperature increases from 20ºC to 100ºC?