PHYSICS 336:
I.
TEST ON CIRCUIT THEORY
NAME _________________________
MULTIPLE GUESS: CIRCLE the LETTER of the MOST correct choice for each
of the following questions.
Questions 1 thru 9 refer to the following circuit.
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Battery delivers a constant
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voltage always
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10 Ohms 20 Ohms 30 Ohms
1.
2.
3.
4.
5.
6.
7.
8.
9.
Across which resistor will the potential difference be the least?
a. 10 Ohm, b. 20 Ohm, c. 30 Ohm, d. all the same.
If the 20 Ohm resistor were removed and the other resistors connected
back together in series, the current in the circuit will - a. be higher
b. be lower, c. remain the same, d. drop to zero.
If the 20 Ohm resistor were removed and the other resistors connected
back together in series, the voltage drop across the 10 Ohm resistor
will - a. be higher, b. be lower, c. remain the same, d. drop to zero.
If the 20 Ohm resistor were removed and the other resistors connected
back together in series, the total voltage across the whole circuit will
- a. be higher, b. be lower, c. remain the same, d. drop to zero.
If the 20 Ohm resistor were removed and the other resistors connected
back together in series, the current through the 10 Ohm resistor will a. be higher, b. be lower, c. remain the same, d. drop to zero.
Suppose a second, identical battery were placed in series with the
battery in the circuit above. What will happen to the total voltage
across the circuit? a. increase, b. decrease, c. remain the same,
d. double.
With these two batteries in the circuit, what happens to the total
current in the circuit? a. it increases, b. it decreases, c. it remains
the same, d. it doubles.
Suppose the second battery were instead connected to each other in
parallel. Assuming the batteries have the same EMF, what will happen to
the total voltage across the circuit? a. it will increase, b. it will
decrease, c. it will remain the same, d. it will double.
With these batteries connected in parallel, what will happen to the
total current in the circuit? a. it will increase, b. it will decrease,
c. it will remain the same, d. it will double.
Questions 10 through 14 refer to the following circuit, which uses a
constant voltage power supply.
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30 Ohms
10.
11.
12.
13.
14.
15.
If a 12 Ohm resistor is added in parallel to the other two resistors,
what happens to the voltage drop across the whole circuit? a. increases,
b. decreases, c. remains the same, d. doubles, e. is cut in half.
If a 12 Ohm resistor is added in parallel to the other two resistors,
what happens to the current in the other branches? a. they will all
increase, b. they will all decrease, c. they will remain the same,
d. the 20 Ohms' current will increase, the 30 Ohms' current will
decrease.
If a 12 Ohm resistor is added in parallel to the other two resistors,
what happens to the total current in the circuit? a. it will increase,
b. it will decrease, c. it will remain the same, d. it will double,
e. it will be cut in half.
If a 12 Ohm resistor is added in parallel to the other two resistors,
what happens to the total resistance in the circuit? a. it will
increase, b. it will decrease, c. it will remain the same, d. it will
double, e. it will be cut in half.
If the resistors in the above circuit were actually light bulbs, what
happens to their brightness if a third light bulb is added in parallel
to the first two? a. they will get brighter, b. they will get dimmer,
c. there will be no change in the brightness.
A voltmeter connected in SERIES with a battery and resistor will
register - a. zero, b. the terminal voltage of the battery, c. the
voltage drop across the internal resistance of the battery, d. the
voltage drop across the resistor.
Answer questions 16 to 18 using the information given below:
In the circuit diagram below all the resistance wires have the same
resistance. Assume that the voltage drop across the circuit always
remains constant, no matter what.
C
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B
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D
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A
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E
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16.
17.
18.
The amount of current flow is greatest through
e. E.
The voltage drop is least across resistor - a.
If resistor B burns out, a. the power usage of
b. resistor C will use more power, c. resistor
d. resistor A will dissipate more power.
- a. A, b. B, c. C, d. D,
A, b. B, c. C, d. E.
E will be unaffected,
C will use no power,
Use the information in the following diagram to answer the next 4
questions.
6V,1Ω battery
5Ω
19.
20.
21.
22.
When the switch is open - a the voltage drop across the resistor is 6V,
b. the voltage drop is less than 6V, b. the voltage drop across the
resistor is greater then when the switch is closed, d. the voltage drop
is zero.
When the switch is closed, the voltage drop across the switch is
a. 6 V, b. less than 6 V, c. 0 V, d. the same as the voltage drop
across the resistor.
The voltage drop across the switch equals the voltage drop across the
power supply - a. when the switch is closed, b. when the switch is open,
c. always, d. never.
If the 5 Ohm resistor is replaced with a 10 Ohm resistor and the switch
is closed, compare the voltage drop and current for the 10 Ohm resistor
to those values for the 5 Ohm resistor. a. voltage drop greater,
current less, b. voltage drop greater, current greater, c. voltage drop
less , current less, e. voltage drop less, current greater, e. voltage
drop same, current less.
III.
PROBLEMS. FULL CREDIT WILL NOT BE GIVEN UNLESS WORK IS SHOWN FOR EACH
OF THE FOLLOWING PROBLEMS.
1.
In the following resistance network the current passing through the 4
Ohm resistance marked R is 0.5 amp.
Determine the current passing
through the 2 Ohm resistor marked R'.
R
4Ω
8Ω
6Ω
6Ω
4Ω
8Ω
6Ω
12Ω
2Ω
R'
2.
In the circuit diagram below, the resistance of every resistor is 240
Ohms. What is the total resistance of the circuit?
3.
Resistor A consists of a 200 m
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long wire of radius 0.0005 m.
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Resistor B consists of a 175 m
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long wire of radius 0.001 m.
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The resistivity of these wires is |
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5E-8 Ohm-meter.
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Wire B dissipates 90 joules of
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energy in 1 minute.
B
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a.
b.
c.
d.
How much charge passes through B in one minute.
When 4 Coulombs of charge pass through A, how much energy does that
charge lose.
What is the voltage drop across the power supply?
What is the unknown EMF?