Question 1

For the circuit shown in the figure,what current does the ideal ammeter read?

Accepted Answer

A)  0.033 A 
B)  0.078 A 
C)  0.23 A 
D)  0.12 A

Question 2

A 400-W computer (including the monitor)is turned on for 8.0 hours per day. If electricity costs 10¢ per kWh,how much does it cost to run the computer annually for a typical 365-day year?

Accepted Answer

A)  $120 
B)  $1200 
C)  $15 
D)  $17 
E)  $150

Question 3

A narrow copper wire of length L and radius b is attached to a wide copper wire of length L and radius 2b,forming one long wire of length 2L.This long wire is attached to a battery,and a current is flowing through it.If the electric field in the narrow wire is E,the electric field in the wide wire is

Accepted Answer

A)  E. 
B)  2E. 
C)  4E. 
D)  E/2. 
E)  E/4.

Question 4

Two light bulbs,B1 and B2,are connected to a battery having appreciable internal resistance as shown in the figure.What happens to the brightness of bulb B1 when we close the switch S?

Accepted Answer

A)  The brightness of B1 increases permanently. 
B)  The brightness of B1 decreases permanently. 
C)  The brightness of B1 does not change. 
D)  The brightness of B1 increases temporarily but gradually decreases back to its original brightness. 
E)  The brightness of B1 decreases temporarily but gradually increases back to its original brightness.

Question 5

The emf and the internal resistance of a battery are as shown in the figure.When the terminal voltage Vab is equal to 17.4 V,what is the current through the battery,including its direction?

Accepted Answer

A)  6.8 A, from b to a 
B)  8.7 A, from b to a 
C)  6.8 A, from a to b 
D)  8.7 A, from a to b 
E)  16 A, from b to a

Question 6

A proton beam that carries a total current of 1.3 mA has 10.0 mm diameter.The current density in the proton beam increases linearly with distance from the center.This is expressed mathematically as
J(r)= J0 (r/R),where R is the radius of the beam and J0 is the current density at the edge.Determine the value of J0.

Accepted Answer

A)  25 A/m2 
B)  6.2 A/m2 
C)  12 A/m2 
D)  17 A/m2

Question 7

When a 20.0-ohm resistor is connected across the terminals of a 12.0-V battery,the voltage across the terminals of the battery falls by 0.300 V.What is the internal resistance of this battery?

Accepted Answer

A)  3.60 Ω 
B)  1.56 Ω 
C)  0.98 Ω 
D)  0.30 Ω 
E)  0.51 Ω

Question 8

The current in a wire varies with time according to the equation I(t)= 6.00 A + (4.80 A/s)t,where t is in seconds.How many coulombs of charge pass a cross section of the wire in the time period between t = 0.00 s and t = 3.00 s?

Accepted Answer

The answer of The current in a wire varies with...

Question 9

What is the maximum current that can be drawn from a 1.50-V battery with an internal resistance of 0.30 ohm?

Accepted Answer

A)  2.5 A 
B)  5.0 A 
C)  0.45 A 
D)  0.20 A 
E)  4.5 A

Question 10

A certain electric furnace consumes 24 kW when it is connected to a 240-V line. What is the resistance of the furnace?

Accepted Answer

A)  1.0 kΩ 
B)  10 Ω 
C)  2.4 Ω 
D)  0.42 Ω 
E)  100 Ω

Question 11

Four resistors are connected across an 8-V DC battery as shown in the figure.The current through the 9-Ω resistor is closest to

Accepted Answer

A)  1 A. 
B)  0.7 A. 
C)  0.5 A. 
D)  0.9 A. 
E)  2 A.

Question 12

In the circuit shown in the figure,all the lightbulbs are identical.Which of the following is the correct ranking of the brightness of the bulbs?

Accepted Answer

A)  B and C have equal brightness, and A is the dimmest. 
B)  A and B have equal brightness, and C is the dimmest. 
C)  A is brightest, C is dimmest, and B is in between. 
D)  A is the brightest, and B and C have equal brightness but less than A. 
E)  All three bulbs have the same brightness.

Question 13

In a certain electroplating process gold is deposited by using a current of 14.0 A for 19 minutes.A gold ion,Au+,has a mass of approximately 3.3 × 10-22 g.How many grams of gold are deposited by this process?

Accepted Answer

A)  33 g 
B)  16 g 
C)  22 g 
D)  28 g 
E)  97 g

Question 14

For the circuit shown in the figure,all quantities are accurate to 3 significant figures.What is the power dissipated in the 2-Ω resistor?

Accepted Answer

A)  5.33 W 
B)  8.0 W 
C)  6.67 W 
D)  2.67 W 
E)  3.56 W

Question 15

A light bulb is connected in the circuit shown in the figure with the switch S open.All the connecting leads have no appreciable resistance and the battery has no internal resistance.When we close the switch,which statements below accurately describe the behavior of the circuit? (There may be more than one correct choice.)

Accepted Answer

A)  The brightness of the bulb will increase. 
B)  The brightness of the bulb will decrease. 
C)  The brightness of the bulb will not change. 
D)  The potential drop across R2 will decrease. 
E)  The potential drop across R2 will not change.

Question 16

For the circuit shown in the figure,I = 0.50 A and R = 12 Ω.What is the value of the emf ε?

Accepted Answer

A)  18 V 
B)  24 V 
C)  6.0 V 
D)  12 V 
E)  48 V

Question 17

A 5.0-Ω resistor and a 9.0-Ω resistor are connected in parallel. A 4.0-Ω resistor is then connected in series with this parallel combination.An ideal 6.0-V battery is then connected across the series-parallel combination of the three resistors.What is the current through
(a)the 4.0-Ω resistor?
(b)the 5.0-Ω resistor?
(c)the 9.0-Ω resistor?

Accepted Answer

The answer of A 5.0-Ω resistor and a 9.0-Ω resistor...

Question 18

A silver wire has a cross sectional area A = 2.0 mm2.A total of 9.4 × 1018 electrons pass through the wire in 3.0 s.The conduction electron density in silver is 5.8 × 1028 electrons/m3 and e = 1.60 × 10-19 C.What is the drift velocity of these electrons?

Accepted Answer

A)  2.7 × 10-5 m/s 
B)  9.1 × 10-5 m/s 
C)  5.2 × 10-5 m/s 
D)  1.1 × 10-5 m/s 
E)  7.4 × 10-5 m/s

Question 19

The emf and the internal resistance of a battery are as shown in the figure.If a current of 8.3 A is drawn from the battery when a resistor R is connected across the terminals ab of the battery,what is the power dissipated by the resistor R?

Accepted Answer

A)  440 W 
B)  700 W 
C)  620 W 
D)  530 W 
E)  790 W

Question 20

The power rating of a 400-Ω resistor is 0.800 W.
(a)What is the maximum voltage that can be applied across this resistor without damaging it?
(b)What is the maximum current this resistor can draw without damaging it?

Accepted Answer

The answer of The power rating of a 400-Ω resistor...

Exam 31: Electric Circuits

For the circuit shown in the figure,what current does the ideal ammeter read?

A 400-W computer (including the monitor) is turned on for 8.0 hours per day. If electricity costs 10¢ per kWh,how much does it cost to run the computer annually for a typical 365-day year?

Two light bulbs,B₁ and B₂,are connected to a battery having appreciable internal resistance as shown in the figure.What happens to the brightness of bulb B₁ when we close the switch S?

The emf and the internal resistance of a battery are as shown in the figure.When the terminal voltage V_ab is equal to 17.4 V,what is the current through the battery,including its direction?