Question 1

How much current is flowing in one of the 10-Ω resistors?

Accepted Answer

A)  0.8 A 
B)  2.0 A 
C)  1.6 A 
D)  2.4 A

Question 2

What is the current through the 8-Ω resistor?

Accepted Answer

A)  1.0 A 
B)  0.50 A 
C)  1.5 A 
D)  2.0 A

Question 3

Which two resistors are in parallel with each other?

Accepted Answer

A)  R and R4 
B)  R2 and R3 
C)  R2 and R4 
D)  R and R1

Question 4

If ε = 20 V,at what rate is thermal energy being generated in the 20-Ω resistor?

Accepted Answer

A)  6.5 W 
B)  1.6 W 
C)  15 W 
D)  26 W

Question 5

A certain capacitor is charged to 10 V and then,at t = 0,allowed to discharge through a certain resistor.There will be a certain time before the voltage across the capacitor reaches 5 V.This time can be decreased for this circuit by increasing:

Accepted Answer

A)  the size of the capacitor. 
B)  the size of the resistor. 
C)  the size of the time constant. 
D)  None of the above.

Question 6

How much power is being dissipated by one of the 10-Ω resistors?

Accepted Answer

A)  24 W 
B)  9.6 W 
C)  16 W 
D)  6.4 W

Question 7

Three resistors,with values of 2,7 and 8 Ω,respectively,are connected in series.What is the overall resistance of this combination?

Accepted Answer

A)  1.3 Ω 
B)  5.7 Ω 
C)  7 Ω 
D)  17 Ω 
E)  ​0.8 Ω

Question 8

What is the potential difference between points a and b?

Accepted Answer

A)  6 V 
B)  8 V 
C)  12 V 
D)  24 V

Question 9

If I1 goes to the right through R1,I2 goes to the right through R2,and I3 goes to the right through R3,what is the resulting equation resulting from applying Kirchhoff's junction rule at point b?

Accepted Answer

A)  I1 + I2 + I3 = 0 
B)  I1 + I2 - I3 = 0 
C)  I1 - I2 + I3 = 0 
D)  I1 - I2 - I3 = 0

Question 10

To find the equivalent resistance of the combination of resistors shown below by the method of possibly repeated applications of combining resistors in series and /or combining resistors in parallel,the first step would be which of the following?

Accepted Answer

A)  Combine the 6.0 Ω and the 7.0 Ω in series. 
B)  Combine either the 4.0 Ω and the 10.0 Ω in parallel or the 7.0 Ω and the 10.0 Ω in parallel first,since either could be the first step with the other the second step. 
C)  Combine the 4.0 Ω and the 10.0 Ω in series. 
D)  Combine the 6.0 Ω,the 4.0 Ω,and the 10.0 Ω in series in a single step.

Question 11

Three resistors connected in parallel each carry currents labeled I1,I2 and I3.Which of the following expresses the value of the total current IT in the combined system?

Accepted Answer

A)  IT = I1 + I2 + I3 
B)  IT = (1/I1 + 1/I2 + 1/I3) 
C)  IT = I1 = I2 = I3 
D)  IT = (1/I1 + 1/I2 + 1/I3)−1

Question 12

Two resistors of values 8 and 17 Ω are connected in parallel.This combination in turn is hooked in series with a 5-Ω resistor.What is the overall resistance of this combination?

Accepted Answer

A)  2.6 Ω 
B)  12.7 Ω 
C)  10.4 Ω 
D)  30 Ω 
E)  ​5.4 Ω

Question 13

If ε = 9.0 V,what is the current in the 15-Ω resistor?

Accepted Answer

A)  0.20 A 
B)  0.30 A 
C)  0 10 A 
D)  0.26 A

Question 14

A circuit contains a 6.0-V battery,a 4.0-Ω resistor,a 0.60-µF capacitor,an ammeter,and a switch all in series.What will be the current reading immediately after the switch is closed?

Accepted Answer

A)  zero 
B)  0.75 A 
C)  1.5 A 
D)  10 A

Question 15

A series RC circuit has a time constant of 1.0 s.The battery has a voltage of 50 V and the maximum current just after closing the switch is 500 mA.The capacitor is initially uncharged.What is the charge on the capacitor 2.0 s after the switch is closed?

Accepted Answer

A)  0.43 C 
B)  0 66 C 
C)  0.86 C 
D)  0.99 C

Question 16

A voltage source of 15 V is connected to a series RC circuit where R = 2 × 106 Ω,and C = 1 µF.Find the amount of time required for the current in the circuit to decay to 6% of its original value.Hint: This is the same amount of time for the capacitor to reach 94% of its maximum charge.

Accepted Answer

A)  1.6 s 
B)  3.6 s 
C)  0.5 s 
D)  5.6 s 
E)  ​11.2 s

Question 17

The following three appliances are connected to a 120-V house circuit: i)toaster,1,250 W,ii)coffee pot,600 W,and iii)microwave,800 W.If all were operated at the same time,what total current would they draw?

Accepted Answer

A)  2.2 A 
B)  44.6 A 
C)  7.4 A 
D)  22.1 A 
E)  ​10.4 A

Question 18

Three resistors connected in series have individual voltages labeled ΔV1,ΔV2 and ΔV3,respectively.Which of the following expresses the value of the total voltage ΔVT taken over the three resistors together?

Accepted Answer

A)  ΔVT = ΔV1 + ΔV2 + ΔV3 
B)  ΔVT = (1/ΔV1 + 1/ΔV2 + 1/ΔV3) 
C)  ΔVT = ΔV1 = ΔV2 = ΔV3 
D)  ΔVT = (1/ΔV1 + 1/ΔV2 + 1/ΔV3)−1

Question 19

A circuit contains a 6.0-V battery,a 4.0-Ω resistor,a 0.60-µF capacitor,an ammeter,and a switch in series.What will be the charge on the capacitor 10 min after the switch is closed?

Accepted Answer

A)  zero 
B)  0.10 μC 
C)  3.6 μC 
D)  2.4 μC

Question 20

A 1 000-V battery,a 3 000-Ω resistor and a 0.50-µF capacitor are connected in series with a switch.The time constant for such a circuit,designated by the Greek letter,τ,is defined as the time required to charge the capacitor to 63% of its capacity after the switch is closed.What is the value of τ for this circuit?

Accepted Answer

A)  6.0 × 109 s 
B)  1.7 × 10−10 s 
C)  1.7 × 10−7 s 
D)  1.5 × 10−3 s

Exam 18: Direct-Current Circuits Sources of EMF