Electric Circuits Practice Test 1

1.

In the circuit below, a 12 V battery is connected in series with a 2 Ω resistor (R1) and in parallel with a branch containing a 4 Ω resistor (R2) and a 6 Ω resistor (R3) in series. What is the current through R2?

[Assume a diagram as described]

a) 1.0 A b) 1.2 A c) 1.5 A d) 2.0 A

2.

A 10 μF capacitor is charged through a 1 kΩ resistor by a 20 V battery. What is the voltage across the capacitor after 10 ms?

a) 7.6 V b) 12.6 V c) 14.5 V d) 18.1 V

3.

In a circuit, a 9 V battery is connected to three resistors in series: 1 Ω, 2 Ω, and 3 Ω. What is the power dissipated in the 2 Ω resistor?

a) 1.5 W b) 2.0 W c) 3.0 W d) 4.5 W

4.

A battery with emf 15 V and internal resistance 1 Ω is connected to a 4 Ω resistor. What is the terminal voltage of the battery?

a) 10.0 V b) 12.0 V c) 13.0 V d) 14.0 V

5.

A 5 μF capacitor is initially charged to 10 V and then discharged through a 2 kΩ resistor. What is the current through the resistor 2 ms after discharge begins?

a) 1.8 mA b) 2.5 mA c) 4.1 mA d) 5.0 mA

6.

Derivation: For two resistors R1 and R2 in series, what is the equivalent resistance?

a) R1 + R2 b) (R1 × R2)/(R1 + R2) c) R1 - R2 d) (R1 + R2)/2

7.

In a two-loop circuit, loop 1 has a 10 V battery and 2 Ω resistor, loop 2 has a 5 V battery and 3 Ω resistor, and the loops share a 1 Ω resistor. What is the current through the shared resistor?

a) 1.0 A b) 1.5 A c) 2.0 A d) 2.5 A

8.

How long does it take for a 20 μF capacitor to reach 63% of its final charge when charged through a 500 Ω resistor?

a) 0.005 s b) 0.01 s c) 0.02 s d) 0.05 s

9.

A battery with emf 12 V and internal resistance 2 Ω is connected to a 10 Ω resistor. What is the power delivered to the external resistor?

a) 10.0 W b) 12.0 W c) 14.4 W d) 16.0 W

10.

Which of the following best describes how an ideal voltmeter and ammeter are connected in a circuit?

a) Voltmeter in parallel, ammeter in series b) Both in series c) Both in parallel d) Voltmeter in series, ammeter in parallel

11.

Derivation: What is the time constant τ for an RC circuit?

a) τ = RC b) τ = R/C c) τ = C/R d) τ = 1/(RC)

12.

A 100 μF capacitor is charged to 50 V and then disconnected from the battery and connected across a 10 Ω resistor. How much energy is dissipated in the resistor?

a) 0.125 J b) 0.25 J c) 0.5 J d) 1.25 J

13.

In a series circuit with three identical resistors and a battery, which resistor dissipates the most power?

a) The first resistor b) The last resistor c) All dissipate the same power d) The one closest to the battery

14.

In an RC circuit, what is the current through the resistor immediately after the switch is closed (t=0)?

a) I = V/R b) I = 0 c) I = V/RC d) I = V/C

15.

In a Wheatstone bridge, R1 = 10 Ω, R2 = 20 Ω, R3 = 30 Ω, R4 = 60 Ω, and a galvanometer connects the midpoints. If a 12 V battery is connected across the bridge, what is the current through the galvanometer?

[Assume a diagram as described]

a) 0 A b) 0.05 A c) 0.10 A d) 0.20 A

16.

A 20 μF capacitor is charged to 30 V and then discharged through a 5 kΩ resistor. How much energy is dissipated in the resistor after a long time?

a) 9.0 mJ b) 12.0 mJ c) 18.0 mJ d) 24.0 mJ

17.

In a two-loop circuit, loop 1 has a 12 V battery and 3 Ω resistor, loop 2 has an unknown battery E and a 6 Ω resistor, and the loops share a 2 Ω resistor. If the current through the 2 Ω resistor is 1 A from loop 1 to loop 2, what is the value of E?

a) 8 V b) 10 V c) 12 V d) 14 V

18.

How long does it take for a 50 μF capacitor to reach 90% of its final voltage when charged through a 1 kΩ resistor?

a) 0.115 s b) 0.230 s c) 0.460 s d) 0.690 s

19.

Two resistors, 10 Ω and 20 Ω, are connected in parallel across a 12 V battery. What is the total power dissipated by the resistors?

a) 7.2 W b) 14.4 W c) 21.6 W d) 24.0 W

20.

Derivation: What is the expression for the current I(t) in a discharging RC circuit with initial voltage V₀?

a) I(t) = (V₀/R) e^-t/RC b) I(t) = (V₀/R) (1 - e^-t/RC) c) I(t) = V₀ e^-t/RC d) I(t) = V₀/RC

21.

A 10 Ω resistor carries a current of 2 A for 5 seconds. How much energy is dissipated as heat?

a) 50 J b) 100 J c) 200 J d) 400 J

22.

At a node in a complex circuit, I₁ = 4 A enters, I₂ = 1 A leaves, I₃ = 2 A enters. What is the value and direction of I₄?

a) 1 A entering b) 1 A leaving c) 5 A entering d) 5 A leaving

23.

In a two-loop circuit, the current in the shared resistor is found to be negative. What does this indicate?

a) The actual current flows opposite to the assumed direction b) The circuit is open c) The batteries are dead d) The resistors are shorted

24.

In an RC circuit, what is the initial current through the resistor when the switch is closed and the capacitor is uncharged?

a) V/R b) 0 c) V/RC d) V/C

25.

A device has a nonlinear I-V curve. Which of the following is true about the power dissipated?

a) P = IV at every instant b) P = I²R always c) P = V²/R always d) P = IV only if the device is ohmic

26.

How long does it take for a 10 μF capacitor to reach half its final charge when charged through a 2 kΩ resistor?

a) 0.014 s b) 0.021 s c) 0.028 s d) 0.035 s

27.

In a two-loop circuit, the shared resistor has a current of 0.5 A and resistance 4 Ω. What is the power dissipated in the shared resistor?

a) 1.0 W b) 2.0 W c) 4.0 W d) 8.0 W

28.

In the circuit below, a 9 V battery is connected in series with a 2 Ω resistor (R1), and in parallel with a branch containing a 4 Ω resistor (R2) and a 6 Ω resistor (R3) in series. What is the voltage drop across R3?

[Assume a diagram as described]

a) 2.0 V b) 3.0 V c) 4.5 V d) 6.0 V

29.

What is the equivalent resistance of three resistors, 2 Ω, 3 Ω, and 6 Ω, connected in parallel?

a) 1.0 Ω b) 2.0 Ω c) 3.0 Ω d) 4.0 Ω

30.

Which of the following best describes an ideal ammeter and voltmeter?

a) Ammeter has zero resistance, voltmeter has infinite resistance b) Ammeter has infinite resistance, voltmeter has zero resistance c) Both have zero resistance d) Both have infinite resistance

Electric Circuits Practice Test 1

15 Challenging Questions – AP Physics C Level