Current
1. A 60-W light bulb operating on a 120-volt household circuit has a resistance closest to
(A) 60 
(B) 120 
(C) 240 
(D) 180 
(E) 360 
2. Which of the following is equivalent to the unit of electrical resistance?
𝐶
𝑉
𝐴
𝑉
𝐶
(A) 𝑉
(B) 𝐴
(C) 𝑉
(D) 𝐶
(E) 𝐽
3. A copper wire has a length L and cross-sectional area A. Another copper wire has a
length of 2L and cross-sectional area 4L. What is the ratio of the resistivity of the second
wire to the resistivity of the first one?
1
1
2
4
1
(A)
(B)
(C)
(D)
(E)
2
4
1
1
1
4. If E is the electric field strength and J is the electric current density, what is the ratio of
𝐸
?
𝐽
(A) Resistance
(B) Resistivity
(C) Voltage
(D) Current
(E) Work
5. Two tungsten wires with different cross-sectional areas and currents are shown on the
diagram. Current I has a cross-sectional are A and runs an electric current I. Current II
has a cross-sectional are 2A and runs an electric current 4I. What is the ration of drift
velocity of particles in the second wire to that in the first one?
2
1
4
1
1
(A) 1
(B) 2
(C) 1
(D) 4
(E) 1
6. The following graphs represent the resistivity as a function of absolute temperature.
Which of the graphs shows the resistivity change of a metallic wire?
(A)
(B)
(C)
(D)
(E)
7. An electric current of 1 A flows through a circuit. The part of the circuit contains a 12 V
battery with an internal resistance of 2 Ω. What is the voltmeter reading?
(A) 4 V (B) 8 V
(C) 10 V (D) 12 V
(E) 16 V
8. An electric current of 2 A flows through a circuit. The part of the circuit contains a 6 V
battery with an internal resistance of 0.5 Ω. What is the voltmeter reading?
(A) 3 V
(B) 4 V
(C) 5 V
(D) 6 V
(E) 7 V
9. An ammeter with an internal resistance of 3.6× 10−3 Ω is design to measure the
maximum current of 0.2 A (full-scale-deflection). It was predicted that the maximum
current in the circuit is 2 A. What must the shut resistance be and how it has to be
connected to the ammeter in order to measure the current in the given circuit?
(A) 3.6× 10−3 Ω in parallel
(B) 3.6× 10−3 in series
(C) 4× 10−4 Ω in parallel
−4
−4
(D) 4× 10 Ω in series
(E) 1.8× 10 Ω in parallel
10. A voltmeter with an internal resistance of 20 Ω is design to measure the maximum
voltage of 2 V (full-scale-deflection). It was predicted that the maximum voltage in the
circuit is 120 V. What must the shut resistance be and how it has to be connected to the
voltmeter in order to measure the voltage in the given circuit?
(A) 11,800 Ω in series (B) 11,800 Ω in parallel (C) 1,180 Ω in series
(D) 1,180 Ω in parallel
(E) 118,000 Ω in series
11. Five different electric circuits are connected to the same battery with negligible
resistance. Which circuit has the least current through the battery?
(A)
(B)
(C)
(D)
(E)
12. Five different electric circuits are connected to the same battery with negligible
resistance. Which circuit produces the greatest power dissipation?
(A)
(B)
(C)
(D)
(E)
13. The emf of a battery is 6 V. When the battery delivers a current of 0.5 A to the external
circuit, the potential difference between the terminals of the battery is 5.8 V. The internal
resistance of the battery is
(A) 0.4 
(B) 4 
(C) 0.6 
(D) 6 
(E) 2 
14. A wire is connected to a battery of a constant voltage and negligible internal resistance.
By decreasing which of the following we can increase the power dissipated in the wire?
(A) L only B) d only
C) L and  only
D) d and  only
E)  only
15. Two resistors with resistance 3  and 2  respectively are connected in series with a 12
V battery. The current in the circuit is 2 A. What is the internal resistance?
(A) 1
(B) 2
(C) 3
(D) 0.5
(E) 0.2
16. Two resistors with resistance of 30  and 6  respectively are connected in parallel with
a 6 V battery. The current in the circuit is 0.25 A. What is the internal resistance?
(B) 1
(B) 2
(C) 3
(D) 4 
(E) 5 
17. Which of the following graphs represents the current as a function of resistance?
(A)
(B)
(C)
(D)
(E)
18. A rheostat is connected across a battery with a constant voltage. Which of the following
graphs represents the power P dissipated by the rheostat as a function of its resistance R?
(A)
(B)
(C)
(C)
(D)
I
II
III
IV
19. Three identical resistors are connected to each other in four different combinations.
Which of the given curcuits has the greatest resistance?
(A) Only I (B) Only II (C) Only III (D) Only IV (E) II and IV
20. A wire of resistance R dissipates power P when a current I passes through it. The wire is
replaced by another wire with resistance 3R. The power dissipated by the new wire when
the same current passes through it is
(A) P/9
(B) P/3
(C) P
(D) 3P
(E) 6P
21. The circuit in the diagram above contains three identical light bulbs connected as shown.
Initially, a switch connected to light bulb I is closed. Which of the following is correct about
brightness of light bulb II and III is correct when the switch is open?
Bulb II
Bulb III
(A) Gets brighter
Gets dimmer
(B) Gets dimmer
Gets brighter
(C) Gets brighter
Gets brighter
(D) Gets dimmer
Gets dimmer
(E) Goes out
Gets brighter
22. What is the current in the circuit above?
(A) 4A
(B) 2A
(C) 1A
(D) 0.5A
(E) 0.25A
23. What the potential difference across the 2  resistor in the circuit above?
(A) 1 V
(B) 2 V
(C) 4 V
(D) 6 V
(E) 18 V
24. The power dissipated in 6  resistor in the circuit above is close to
(A) 10.7 W (B) 5.3 W
(C) 24.5 W (D) 37.2 W (E) 43.4 W
Z
25. Which of the following is true about the current through resistor R and charge in the
capacitor, immediately after the switch is closed?
Current I
Charge Q
(A) Zero
Maximum
(B) Maximum
Zero
(C) Zero
Zero
(D) Maximum
Maximum
(E) Stays unchanged Stays unchanged
26. Which of the following is true about the current through resistor R and charge in the
capacitor, when the switch is closed for a long time?
Current I
Charge Q
(A) Zero
Maximum
(B) Maximum
Zero
(C) Zero
Zero
(D) Maximum
Maximum
(E) Stays unchanged Stays unchanged
27. . A circuit is connected to a 9 V battery with a net resistance of 40.5 Ω. How much
energy is dissipated by the circuit in time interval of 1 min?
(A) 120 J
(B) 240J
(C) 360 J
(D) 60 J
(E) 30 J
28. A resistor R = 1× 106 Ω, a capacitor C = 1 nF are connected in series with a battery V
and switch S. What is the time constant of the circuit?
(A) 10−6
(B) 10−3
(C) 10−9
(D) 106
(E) 103
29. In order to measure the current and voltage through a circuit how must an ammeter and
voltmeter be connected to a circuit?
Ammeter
Voltmeter
(A)
in parallel
in series
(B)
in parallel
in parallel
(C)
in series
in series
(D)
in series
in parallel
(E)
none from the above
none from the above
30. A battery with internal resistance R and an electromotive force ε supplies a current I to a
light bulb of resistance r. The power dissipated by the circuit is
(A)
ε2
𝑅+𝑟
(B)
(ε – IR)2
𝑅
(C)
(ε – IR)2
𝑅+𝑟
(D)
ε2
𝑅
(E)
(ε +IR)2
𝑅+𝑟
Answers
1. C
2. B
3. E
4. B
5. B
6. B
7. C
8. E
9. C
10. C
11. E
12. B
13. A
14. D
15. A
16. D
17. D
18. C
19. C
20. D
21. A
22. B
23. C
24. A
25. B
26. A
27. A
28. B
29. D
30. A