Question 1

The power rating of a resistor is 0.800 W. If the value of the resistor is 400 Ω, what is the maximum voltage?

Accepted Answer

A)  110 V 
B)  17.9 V 
C)  170 V 
D)  1.80 V 
A)  110 V 
B)  17.9 V 
C)  170 V 
D)  1.80 V

Question 2

Capacitances of 10. μF and 20. μF are connected in parallel, and this pair is then connected in series with a 30. μF capacitor. What is the equivalent capacitance of this arrangement?

Accepted Answer

The answer of Capacitances of 10. μF and 20. μF...

Question 3

FIGURE 21-19  
-Four capacitors are connected across a 90-V DC source as shown in Figure 21-19. What is the charge on the 3.0-μF capacitor?

Accepted Answer

A)  180 μC 
B)  120 μC 
C)  90 μC 
D)  160 μC 
E)  240 μC 
A)  180 μC 
B)  120 μC 
C)  90 μC 
D)  160 μC 
E)  240 μC

Question 4

The length of a certain wire is doubled and at the same time its radius is increased by a factor of 4. What is the change in the resistance of this wire?

Accepted Answer

A)  It is reduced by a factor of 8. 
B)  It increases by a factor of 8. 
C)  It is reduced by a factor of 4. 
D)  It increases by a factor of 4. 
E)  It stays the same. 
A)  It is reduced by a factor of 8. 
B)  It increases by a factor of 8. 
C)  It is reduced by a factor of 4. 
D)  It increases by a factor of 4. 
E)  It stays the same.

Question 5

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel to the first, the time constant of the new RC circuit will be

Accepted Answer

A)  the same as before. 
B)  twice as large as before. 
C)  three times a large as before. 
D)  one-half as large as before. 
E)  one-fourth as large as before. 
A)  the same as before. 
B)  twice as large as before. 
C)  three times a large as before. 
D)  one-half as large as before. 
E)  one-fourth as large as before.

Question 6

A 200-W light bulb is connected across 110 V. What current will flow through this bulb?

Accepted Answer

A)  0.90 A 
B)  0.36 A 
C)  0 A 
D)  0.60 A 
E)  1.8 A 
A)  0.90 A 
B)  0.36 A 
C)  0 A 
D)  0.60 A 
E)  1.8 A

Question 7

When the current through a resistor is increased by a factor of 4, the power dissipated by it

Accepted Answer

A)  decreases by a factor of 4. 
B)  decreases by a factor of 16. 
C)  increases by a factor of 16. 
D)  increases by a factor of 4. 
E)  remain unchanged. 
A)  decreases by a factor of 4. 
B)  decreases by a factor of 16. 
C)  increases by a factor of 16. 
D)  increases by a factor of 4. 
E)  remain unchanged.

Question 8

The length of a certain wire is doubled while its radius is kept constant. What is the change in the resistance of this wire?

Accepted Answer

A)  It stays the same. 
B)  It is doubled. 
C)  It is tripled. 
D)  It is quadrupled. 
E)  It is reduced by a factor of 2. 
A)  It stays the same. 
B)  It is doubled. 
C)  It is tripled. 
D)  It is quadrupled. 
E)  It is reduced by a factor of 2.

Question 9

You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the largest possible resistance, you should attach the leads to the opposite faces that measure

Accepted Answer

A)  3 cm × 5 cm. 
B)  3 cm × 8 cm. 
C)  5 cm × 8 cm. 
D)  Any pair of faces produces the same resistance. 
A)  3 cm × 5 cm. 
B)  3 cm × 8 cm. 
C)  5 cm × 8 cm. 
D)  Any pair of faces produces the same resistance.

Question 10

What potential difference is required to cause 2.0 A to flow through a resistance of 8.0 Ω?

Accepted Answer

The answer of What potential difference is required to cause...

Question 11

Capacitors in series share the same charge and capacitors in parallel share the same voltage.

Accepted Answer

A) True 
 B)False

Question 12

Two 100 W lightbulbs are to be connected to a 120 V source. What is the current, potential difference, and dissipated power for each when they are connected:
(a) in parallel (the normal arrangement)?
(b) in series?

Accepted Answer

(a)0.83 A in each; 1

Question 13

The power rating of a resistor is 0.80 W. If the value of the resistor is 400 Ω, what is the maximum current it can draw?

Accepted Answer

A)  45 mA 
B)  18 mA 
C)  4.4 mA 
D)  2.0 mA 
E)  320 mA 
A)  45 mA 
B)  18 mA 
C)  4.4 mA 
D)  2.0 mA 
E)  320 mA

Question 14

FIGURE 21-4  
-A 100 V DC signal is applied to four resistors as shown in Figure 21-4. The values of the resistors are 20 Ω, 40 Ω, 60 Ω, and 80 Ω. What is the voltage across the 40 Ω resistor?

Accepted Answer

A)  20 V 
B)  40 V 
C)  60 V 
D)  80 V 
E)  100 V 
A)  20 V 
B)  40 V 
C)  60 V 
D)  80 V 
E)  100 V

Question 15

An RC circuit consists of 2.0 MΩ in series with a capacitor. When connected to a battery, the capacitor becomes 25% charged in 1.5 seconds. What is the capacitance value?

Accepted Answer

The answer of An RC circuit consists of 2.0 MΩ...

Question 16

A 8.0 μF capacitor is connected in series with a 6.0 kΩ resistor across a 20-V DC source and a switch. What is the time constant of this RC circuit?

Accepted Answer

A)  9.0 ms 
B)  12 ms 
C)  40 ms 
D)  18 ms 
E)  48 ms 
A)  9.0 ms 
B)  12 ms 
C)  40 ms 
D)  18 ms 
E)  48 ms

Question 17

The length of a certain wire is doubled and at the same time its radius is tripled. What is the change in the resistance of this wire?

Accepted Answer

A)  It stays the same. 
B)  It is reduced by a factor of 4.5. 
C)  It is doubled. 
D)  It is tripled. 
E)  It is quadrupled. 
A)  It stays the same. 
B)  It is reduced by a factor of 4.5. 
C)  It is doubled. 
D)  It is tripled. 
E)  It is quadrupled.

Question 18

The length of a certain wire is doubled and at the same time its radius is reduced by a factor of 2. What is the change in the resistance of this wire?

Accepted Answer

A)  It is doubled. 
B)  It is quadrupled. 
C)  It increases by a factor of 6. 
D)  It increases by a factor of 8. 
E)  It is reduced by a factor of 2. 
A)  It is doubled. 
B)  It is quadrupled. 
C)  It increases by a factor of 6. 
D)  It increases by a factor of 8. 
E)  It is reduced by a factor of 2.

Question 19

FIGURE 21-3  
-A 4-Ω resistor is connected in parallel with a 12-Ω resistor and this combination is connected to a DC power supply with voltage V as shown in Figure 21-3. If the total current in this circuit is 2 A, what is the value of voltage V?

Accepted Answer

A)  2 V 
B)  3 V 
C)  6 V 
D)  1.5 V 
E)  None of the other answers is correct. 
A)  2 V 
B)  3 V 
C)  6 V 
D)  1.5 V 
E)  None of the other answers is correct.

Question 20

The potential difference between the ends of a resistor is 9 V when a current of 1 A flows through it. What is the value of that resistor?

Accepted Answer

A)  9 Ω s 
B)  9 Ω/s 
C)  9 V∙s 
D)  9 V/s 
E)  9 Ω 
A)  9 Ω s 
B)  9 Ω/s 
C)  9 V∙s 
D)  9 V/s 
E)  9 Ω

Exam 21: Electric Current and Direct-Current Circuits

The power rating of a resistor is 0.800 W. If the value of the resistor is 400 Ω, what is the maximum voltage?

Capacitances of 10. μF and 20. μF are connected in parallel, and this pair is then connected in series with a 30. μF capacitor. What is the equivalent capacitance of this arrangement?

FIGURE 21-19 -Four capacitors are connected across a 90-V DC source as shown in Figure 21-19. What is the charge on the 3.0-μF capacitor?

The length of a certain wire is doubled and at the same time its radius is increased by a factor of 4. What is the change in the resistance of this wire?

A capacitor C is connected in series with a resistor R across a battery and an open switch. If a second capacitor of capacitance 2C is connected in parallel to the first, the time constant of the new RC circuit will be

A 200-W light bulb is connected across 110 V. What current will flow through this bulb?

When the current through a resistor is increased by a factor of 4, the power dissipated by it

The length of a certain wire is doubled while its radius is kept constant. What is the change in the resistance of this wire?

You are given a copper bar of dimensions 3 cm × 5 cm × 8 cm and asked to attach leads to it in order to make a resistor. If you want to achieve the largest possible resistance, you should attach the leads to the opposite faces that measure

What potential difference is required to cause 2.0 A to flow through a resistance of 8.0 Ω?

Capacitors in series share the same charge and capacitors in parallel share the same voltage.

Two 100 W lightbulbs are to be connected to a 120 V source. What is the current, potential difference, and dissipated power for each when they are connected: (a) in parallel (the normal arrangement)? (b) in series?

The power rating of a resistor is 0.80 W. If the value of the resistor is 400 Ω, what is the maximum current it can draw?

FIGURE 21-4 -A 100 V DC signal is applied to four resistors as shown in Figure 21-4. The values of the resistors are 20 Ω, 40 Ω, 60 Ω, and 80 Ω. What is the voltage across the 40 Ω resistor?

An RC circuit consists of 2.0 MΩ in series with a capacitor. When connected to a battery, the capacitor becomes 25% charged in 1.5 seconds. What is the capacitance value?

A 8.0 μF capacitor is connected in series with a 6.0 kΩ resistor across a 20-V DC source and a switch. What is the time constant of this RC circuit?

The length of a certain wire is doubled and at the same time its radius is tripled. What is the change in the resistance of this wire?

The length of a certain wire is doubled and at the same time its radius is reduced by a factor of 2. What is the change in the resistance of this wire?

FIGURE 21-3 -A 4-Ω resistor is connected in parallel with a 12-Ω resistor and this combination is connected to a DC power supply with voltage V as shown in Figure 21-3. If the total current in this circuit is 2 A, what is the value of voltage V?

The potential difference between the ends of a resistor is 9 V when a current of 1 A flows through it. What is the value of that resistor?

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