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Name: ________________________
Grade 12 Physics – Electric Circuits Test
For the following questions, show your work and round to the appropriate number of significant figures.
Multiple Choice: Choose the best answer. (1 mark each)
1. Which of the following statements about this circuit is TRUE?
Current
A1
R2
R1
A3
A2
A.
B.
C.
D.
The reading of A1 is greater than A2
A lower current flows through A3 than comes out of the battery
The reading on A2 is about the same as the reading on A3
R2 slows the electrons down so the reading on A3 must be less than that on A2
2. The diagram below represents part of an electric circuit containing three resistors. What
is the equivalent resistance of this part of the circuit?
A. 0.67 Ω
B. 6.3 Ω
C. 19 Ω
D. 1.5 Ω
3. A girl has 3 equal resistors each of value 6 . She has found that by connecting all of
them in series and parallel combinations she can produce several different values of their
total resistance. The only values possible are:
A. 18 , 12 , 6 , 3 ,
B. 18 , 9 , 4 , 2 
C. 18 , 9 , 6 , 3 
D. 18 , 4 , 2 , 1 
4. As the number of resistors in a parallel circuit is increased, what happens to the
equivalent resistance of the circuit and total current in the circuit?
A. Both equivalent resistance and total current decrease.
B. Both equivalent resistance and total current increase.
C. Equivalent resistance decreases and total current increases.
D. Equivalent resistance increases and total current decreases.
L. Mann
PHY40S
5. Three equal resistance lamps are connected in the series and parallel arrangement shown
with ammeters A1 to A4 placed in the circuit as indicated. A 9 V battery causes a current
of 450 mA to flow when it is connected to just one of the lamps.
9V
A1
L1
A2
A4
L2
L3
A3
Which set (row) of current readings would be correct for the circuit shown above?
A
B
C
D
A1 (mA)
450
300
300
450
A2 (mA)
225
300
150
150
A3 (mA)
225
300
150
150
A4 (mA)
450
300
300
300
6. A circuit has 2.7A of current flowing through it. How many electrons are flowing through
this circuit it 1.5s?
A. 1.6 × 1019
B. 4.05
C. 6.48 × 10-19
D. 2.53 × 1019
7. The resistivity of nichrome wire is quoted as 1.1 x 10-6 m. The length of 1mm diameter
nichrome wire needed to make up a 1.0  resistor would be about:
A. 0.27 m
B. 0.7 m
C. 29 m
D. 1430 m
DC Circuits
1. Find the current through each resistor by using the property that current is inversely
proportional to resistance. (2 marks)
I1 = __________
I2 = __________
L. Mann
PHY40S
Series and Parallel Circuits
2. Calculate all unknowns in the following circuit. You do not need to show your work.
(6 marks – 0.5 each)
V1 =
IT =
I1 =
Req =
R1 = 
V2 =
12 V
A
R2 = 
R3= 
R4= 
R5 = 
3
I2 =
B
V3 =
I3 =
V4 =
I4 =
V5 =
I5 =
Equivalent Resistance
3. Calculate the equivalent resistance of the group of resistors shown in the diagram below.
You must show work for full marks. (5 marks)
L. Mann
PHY40S
Power
4. How much heat does a lamp with a resistance of 88Ω give off if it is connected to a
source providing 15V for 2.5 hours? (3 marks)
5. A 240.0Ω and 90.0Ω resistor are connected in parallel with a 120V source and then
reassembled to be in series with the source. Calculate the total power output of the two
resistors for each setup. (3 marks)
Resistances of a Conductor
6. A 31m long extension cord made of copper is designed to carry a current of 15A. What
must be the radius of this wire if no more than 5.0V of potential decrease can be occur
when 15A of current is in this wire? (Resistivity of copper is 1.68 x 10-8 Ωm.) (3 marks)
Reoccurring Processes: there will be 2 marks given for using the correct sig figs, units, etc. in your final
answers. There will be 0.5 marks taken off for each mistake, to a maximum of 2 marks. I will not take off
marks for sig figs on questions 2, 3.
L. Mann
PHY40S