Review of Electricity
Assignment 2
Name:___________________
Show all workings for multiple choice.
1
A circuit consists of a battery and three resistors. The resistors are of unequal value and are connected
in parallel. What is equal to the sum of the currents through the resistors?
(A)
the current through the battery
(B)
the current through one resistor
(C)
three times the current through one resistor
(D)
zero
2
What happens when a parallel resistor is added to a circuit?
(A)
The total resistance decreases.
(B)
The total resistance increases.
(C)
The total voltage decreases.
(D)
The total voltage increases.
3
Which combination of three identical resistors has the least equivalent resistance?
4
Which arrangement of identical resistors would draw the most current when connected to the same
potential difference?
5
The diagram below shows a circuit containing a battery, a switch
three ammeters, a voltmeter, and two resistors. When the switch is
closed, what is the current through ammeter 3?
(A)
(B)
(C)
(D)
Equal to the current through ammeter A2.
Equal to the current through the voltmeter.
Half the current through ammeter A2
Twice the current through ammeter A2.
6
If R9 > R10 then which statement concerning
the circuit would be correct?
(A)
No current would flow through R9;
it would all go through R10.
(B)
The current through the two resistors
is the same regardless of the resistance.
(C)
The current through R9 is less than
the current through R10.
(D)
The current through R9 is greater than
the current through R10.
7
A simple series circuit contains a resistor of resistance R and a battery. What is true if a second
identical resistor is connected in parallel with R?
(A)
The current flowing through R will decrease.
(B)
The current flowing from the battery will increase.
(C)
The voltage drop across R will decrease.
(D)
The voltage supplied by the battery will increase.
8
When switch, S is open to shut off bulb 2 in the figure
to the right
(A)
bulb 1 will get brighter.
(B)
bulb 1 will get dimmer.
(C)
bulb 1 will not be affected.
(D)
bulb 1 will also be shut off.
10
What is the total resistance between points A and B, as shown in the picture? Each resistor is rated at
10.0 W.
(A)
(B)
(C)
(D)
10.0 W
20.0 W
30.0 W
50.0 W
11
If four 20 Ù resistors are connected in parallel, what is the equivalent resistance?
(A)
5Ù
(B)
10 Ù
(C)
20 Ù
(D)
80 Ù
12
Three identical resistors are connected in parallel to a battery. If a current of 12 A flows from the
battery, how much current flows through any one of the resistors?
(A)
0
(B)
4A
(C)
12 A
13
A circuit contains 2 resistors connected to a battery as
shown in the figure. The current leaving the battery is
0.50 A. What is the potential difference of the battery?
(A)
0.10 V
(B)
2.5 V
(C)
5.0 V
(D)
10.0 V
14
Two 4 W resistors are connected to a 12 V source as shown
in the picture. What is the current in segment XY?
(A)
0.75 A
(B)
1.5 A
(C)
2.0 A
(D)
3.0 A
(D)
36 A
15
Two resistors are arranged in a circuit that carries a total current of 15 A as shown in thefigure.
Which of the entries in the following table is correct?
16
A 36 volt battery, a small lamp, and a resistor of 2.0 W are connected
as shown in the picture. The total current in the circuit is 3.0 A. What
is the resistance R of the small lamp?
(A)
2.0 W
(B)
6.0 W
(C)
10.0 W
(D)
12.0 W
17
A series circuit consists of a battery and three resistors
arranged as shown in the diagram below. What is the
potential difference Vxy ?
(A)
3.0 V
(B)
6.0 V
(C)
9.0 V
(D)
21 V
18
Which best describes the relationship between the two circuits below if all resistors are identical, V1
and V2 are readings from ideal voltmeters, and I1 and I2 are readings from ideal ammeters?
19
For the circuit shown below, what is the effect on the ammeter
and voltmeter readings when the switch is closed?
Ammeter reading Voltmeter reading
(A)
decreases
decreases
(B)
decreases
increases
(C)
increases
decreases
(D)
increases
increases
20
A toaster is already plugged in to an electrical outlet. What will happen to the current if the circuit of
a lamp is plugged into the same outlet?
(A)
(B)
(C)
(D)
It will decrease.
It will increase.
It will remain the same.
The answer depends on the power rating of the lamp.
21
A 120 V power line is protected by a 15 A fuse. What is the maximum number of 500 W lamps that
can be connected in parallel on the circuit?
(A)
1
(B)
2
(C)
3
(D)
4
22
What happens to the power dissipated by a circuit of constant resistance if the voltage across the
circuit is doubled?
(A)
decreases to one half its original value
(B)
decreases to one quarter its original value
(C)
doubles
(D)
quadruples
23
A refrigerator compressor draws 2.0 A from a 120 V source and operates, on average, 30 min/h.
What is the approximate hourly cost of operation the refrigerator if the cost of electrical energy is
8 ¢ /KWAh?
(A)
0.01¢
(B)
0.1¢
(C)
1¢
(D)
10¢
24
If electricity costs $0.10/ kwh, what would be the cost of operating a 5000 W stove for 2 hours?
(A)
25
$0.10
(B)
$1.00
(C)
$10.00
(D)
$1000.00
If a toaster has a resistance of 10 Ù and the potential difference is 120 V, what power does it use
while toasting a slice of bread?
(A)
1.1 × 103 W
(B)
1.4 ×103 W
(C)
1.2 × 105 W
(D)
1.3 × 105 W
26
A resistor dissipates 1.5 W when it is connected to a battery with a potential difference of
12 V. What is the resistance of the resistor?
(A)
8.0 Ù
(B)
18 Ù
(C)
96 Ù
(D)
220 Ù
27
If the potential drop across an operating 300 watt floodlight is 120 volts, what is the current through
the floodlight?
(A)
0.40 A
(B)
2.5 A
(C)
7.5 A
(D)
4.8 A
28
If a 1.2 × 103 W hair dryer has a 10.0 Ù resistance, how much current will it draw?
(A)
0.091 A
(B)
11 A
(C)
12 A
(D)
120 A
29
What is the power dissipated by the 5.0 Ù resistor in the circuit
below?
(A)
3.5 W
(B)
4.2 W
(C)
7.2 W
(D)
130 W
30
How much electrical energy does a 75 W motor use in 15 minutes?
(A)
1.1 × 103 J
(B)
1.9 × 103 J
(C)
6.8 × 104 J
(D)
2.7 × 105 J
31.
Two resistors have the same power dissipated by them. The potential drop across resistor A is twice
that across resistor B. If the resistance of resistor B is R, what is the resistance of A?
(A)
R/2
(B)
R
(C)
2R
(D)
4R
32
A 12 V battery is connected in a circuit that contains twenty-four 40.0-Ù resistors in parallel. What is
the current through each resistor?
33
A circuit containing four 30.0 Ù resistors connected
to a 12 V battery is shown.
(A) What is the total equivalent resistance of the circuit?
(B) What is the voltage drop across R4?
34
Use the circuit diagram below to answer the questions that
follow. (assume 2 sig figs)
(A)
What is the equivalent resistance between the points
A and B?
(B)
What is the current through the 2 Ù resistor?
35
36
A 39 V source is connected to three resistors as shown in the
picture.
(A)
Find the total resistance of the circuit.
(B)
The total current in the circuit.
(C)
The potential difference across R3.
Three identical 10.0 Ù light bulbs are connected
to a 60.0 V source as shown in the diagram.
(A)
Calculate total resistance and current for the circuit shown
above in each instance.
i) The switch is open
ii) The switch is closed
(B)
Compare the brightness of the bulbs when the switch is open and closed. Justify your answer.
37
How could four identical light bulbs be wired to a 12 V battery in a circuit to achieve each of the
following?
(A)
Maximum current is drawn from the battery.
(B)
Maximum electrical resistance is achieved.
(C)
Light will still be produced even if one of the lights blow.
38
A home owner wants to put Christmas tree lights on his house. The string has 300 lights, with each
light rated at 25 W. If the homeowner runs the lights for 3 weeks at 6 hours each day, how much will
it cost him to operate the lights? The price of elecrtical energy is 7 ¢ / kWh.
39
The picture shows a series-parallel
combination of 5 resistors connected to a
battery with a potential difference of 8.0 V.
Use the values indicated in the
figure to find each quantity.
(A)
The current through R4
(B)
The voltage drop across R1
40
41
For the circuit below, R3 = 400.0 Ù and R1 = R2. The total
power dissipated by the circuit is 0.16 W and the total
current entering the circuit is 0.040 A.
(A)
Find RT.
(B)
Find VT.
(C)
Find R1 and R2.
(D)
Find P1.
Four resistors and a 26 V power supply are arranged as shown in the circuit diagram.
(a)
Determine the equivalent resistance for this circuit.
(b)
Find the current through R3