Question 1

Consider a 1.40 kW hair dryer operated on 120. V. What is
(a) the current?
(b) its resistance?

Accepted Answer

The answer of Consider a 1.40 kW hair dryer operated...

Question 2

A 100-V DC signal is applied to a series circuit composed of four equal resistors 10 Ω each. What is the voltage across each resistor?

Accepted Answer

A)  10 V 
B)  15 V 
C)  20 V 
D)  25 V 
E)  50 V 
A)  10 V 
B)  15 V 
C)  20 V 
D)  25 V 
E)  50 V

Question 3

An electric device delivers a current of 5.0 A for 10 seconds. How many electrons flow through this device?

Accepted Answer

A)  0.20 
B)  20 
C)  2.0 
D)  3.1 × 1020 
E)  31 × 1020 
A)  0.20 
B)  20 
C)  2.0 
D)  3.1 × 1020 
E)  31 × 1020

Question 4

A 100-W light bulb is connected to a 110-V source. What is the resistance of this bulb?

Accepted Answer

A)  100 Ω 
B)  8.00 × 10-3 Ω 
C)  6.00 × 10-3 Ω 
D)  121 Ω 
E)  242 Ω 
A)  100 Ω 
B)  8.00 × 10-3 Ω 
C)  6.00 × 10-3 Ω 
D)  121 Ω 
E)  242 Ω

Question 5

List two conditions for producing an electric current in a circuit.

Accepted Answer

(1)must supply a pot

Question 6

The length of a certain wire is doubled while the radius is reduced by a factor of 4. What is the change in the resistance of this wire?

Accepted Answer

A)  It stays the same. 
B)  It is quadrupled. 
C)  It is increased by a factor of 32. 
D)  It is increased by a factor of 16. 
E)  It is increased by a factor of 8. 
A)  It stays the same. 
B)  It is quadrupled. 
C)  It is increased by a factor of 32. 
D)  It is increased by a factor of 16. 
E)  It is increased by a factor of 8.

Question 7

A combination of 2.0 Ω in series with 4.0 Ω is connected in parallel with 3.0 Ω. What is the equivalent resistance?

Accepted Answer

The answer of A combination of 2.0 Ω in series...

Question 8

The power rating of a resistor is 0.800 W. The value of the resistor is 400 Ω.
(a) What is the maximum voltage?
(b) What is the maximum current it can draw?

Accepted Answer

The answer of The power rating of a resistor is...

Question 9

Which one of the following is the correct expression for electric current?

Accepted Answer

A)  I = ΔC/Δt 
B)  I = ΔR/Δt 
C)  I = ΔV/Δt 
D)  I = ΔQ/Δt 
E)  None of the other answers is correct. 
A)  I = ΔC/Δt 
B)  I = ΔR/Δt 
C)  I = ΔV/Δt 
D)  I = ΔQ/Δt 
E)  None of the other answers is correct.

Question 10

FIGURE 21-18  
-A 2.0 μF and a 4.0 μF capacitor are connected in series across an 8.0-V DC source. What is the charge on the 2.0 μF capacitor?

Accepted Answer

A)  2.0 μC 
B)  4.0 μC 
C)  12 μC 
D)  11 μC 
E)  25 μC 
A)  2.0 μC 
B)  4.0 μC 
C)  12 μC 
D)  11 μC 
E)  25 μC

Question 11

FIGURE 21-14  
-A number of resistors are connected across points A and B as shown in Figure 21-14. What is the equivalent resistance between points A and B?

Accepted Answer

A)  4 Ω 
B)  6 Ω 
C)  8 Ω 
D)  10 Ω 
E)  12 Ω 
A)  4 Ω 
B)  6 Ω 
C)  8 Ω 
D)  10 Ω 
E)  12 Ω

Question 12

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 4.0-μF capacitor?

Accepted Answer

A)  68 μC 
B)  90 μC 
C)  240 μC 
D)  180 μC 
E)  120 μC 
A)  68 μC 
B)  90 μC 
C)  240 μC 
D)  180 μC 
E)  120 μC

Question 13

Which one of the following is the correct statement regarding the resistance?

Accepted Answer

A)  The resistance of a conductor decreases with temperature. 
B)  The resistance of a semiconductor increases with temperature. 
C)  The resistance of a wire is directly proportional to the length of the wire. 
D)  All of the above statements are correct. 
E)  None of the above statements is correct. 
A)  The resistance of a conductor decreases with temperature. 
B)  The resistance of a semiconductor increases with temperature. 
C)  The resistance of a wire is directly proportional to the length of the wire. 
D)  All of the above statements are correct. 
E)  None of the above statements is correct.

Question 14

FIGURE 21-5  
-Three resistors of values 2 Ω, 6 Ω and 12 Ω are connected across a DC voltage source as shown in Figure 21-5. If the total current through the circuit is 2.0 A, what is the applied voltage?

Accepted Answer

A)  6.0 V 
B)  3.0 V 
C)  2.0 V 
D)  2.7 V 
E)  1.5 V 
A)  6.0 V 
B)  3.0 V 
C)  2.0 V 
D)  2.7 V 
E)  1.5 V

Question 15

Two capacitors of 4 μF and 8 μF are connected in parallel. What is the equivalent capacitance of this system of capacitors?

Accepted Answer

A)  0.4 μF 
B)  12 μF 
C)  2.7 μF 
D)  4 μF 
E)  6 μF 
A)  0.4 μF 
B)  12 μF 
C)  2.7 μF 
D)  4 μF 
E)  6 μF

Question 16

FIGURE 21-17  
-Three capacitors are connected as shown in Figure 21-17. What is the equivalent capacitance between points A and B?

Accepted Answer

A)  1.7 μF 
B)  4.0 μC 
C)  7.1 μF 
D)  12 μF 
E)  8.0 μF 
A)  1.7 μF 
B)  4.0 μC 
C)  7.1 μF 
D)  12 μF 
E)  8.0 μF

Question 17

An RC circuit is connected across a DC voltage source through an open switch. As soon as the switch is closed, the capacitor charges linearly as a function of time.

Accepted Answer

A) True 
 B)False

Question 18

An RC circuit is connected across a DC voltage source through an open circuit and a switch. As soon as the switch is closed, the charge on the capacitor increases but the voltage across it decreases as a function of time.

Accepted Answer

A) True 
 B)False

Question 19

The resistance of a 100-cm wire of cross sectional area 2 × 10-6 m2 is 400 Ω. What is the resistivity of the material of this wire?

Accepted Answer

A)  0.8 × 10-4 Ωm 
B)  8 × 10-4 Ωm 
C)  0.8 × 10-5 Ωm 
D)  0.8 × 10-6 Ωm 
E)  8 × 10-6 Ωm 
A)  0.8 × 10-4 Ωm 
B)  8 × 10-4 Ωm 
C)  0.8 × 10-5 Ωm 
D)  0.8 × 10-6 Ωm 
E)  8 × 10-6 Ωm

Exam 21: Electric Current and Direct-Current Circuits

Consider a 1.40 kW hair dryer operated on 120. V. What is (a) the current? (b) its resistance?

A 100-V DC signal is applied to a series circuit composed of four equal resistors 10 Ω each. What is the voltage across each resistor?

An electric device delivers a current of 5.0 A for 10 seconds. How many electrons flow through this device?

A 100-W light bulb is connected to a 110-V source. What is the resistance of this bulb?

List two conditions for producing an electric current in a circuit.

The length of a certain wire is doubled while the radius is reduced by a factor of 4. What is the change in the resistance of this wire?

A combination of 2.0 Ω in series with 4.0 Ω is connected in parallel with 3.0 Ω. What is the equivalent resistance?

The power rating of a resistor is 0.800 W. The value of the resistor is 400 Ω. (a) What is the maximum voltage? (b) What is the maximum current it can draw?

Which one of the following is the correct expression for electric current?

FIGURE 21-18 -A 2.0 μF and a 4.0 μF capacitor are connected in series across an 8.0-V DC source. What is the charge on the 2.0 μF capacitor?

FIGURE 21-14 -A number of resistors are connected across points A and B as shown in Figure 21-14. What is the equivalent resistance between points A and B?

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 4.0-μF capacitor?

Which one of the following is the correct statement regarding the resistance?

FIGURE 21-5 -Three resistors of values 2 Ω, 6 Ω and 12 Ω are connected across a DC voltage source as shown in Figure 21-5. If the total current through the circuit is 2.0 A, what is the applied voltage?

Two capacitors of 4 μF and 8 μF are connected in parallel. What is the equivalent capacitance of this system of capacitors?

FIGURE 21-17 -Three capacitors are connected as shown in Figure 21-17. What is the equivalent capacitance between points A and B?

An RC circuit is connected across a DC voltage source through an open switch. As soon as the switch is closed, the capacitor charges linearly as a function of time.

An RC circuit is connected across a DC voltage source through an open circuit and a switch. As soon as the switch is closed, the charge on the capacitor increases but the voltage across it decreases as a function of time.

The resistance of a 100-cm wire of cross sectional area 2 × 10-6 m2 is 400 Ω. What is the resistivity of the material of this wire?

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The resistance of a 100-cm wire of cross sectional area 2 × 10^-6m² is 400 Ω. What is the resistivity of the material of this wire?