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Comprehensive Worksheet: Electric Current and Circuits
Worksheet: Resisting the Flow
(you will need to use your reference tables for this worksheet)
1. A copper wire is 220 m long with an area of 1.26 x 10 -5 m2. What is the resistance of the wire?
2. An aluminum wire has an area of 4.89 x 10-6 m2. If the wire has a resistance of 5.0 , how long is it?
3. A nichrome wire has an length of 5.66 m and has a resistance of 0.23 .
a) What is the area of the wire?
b) What is the diameter of the wire?
4. A Tungsten wire has a diameter of 0.018 mm. How long of a wire would be needed to supply 3.0  of resistance?
5. The reference tables provide the resistivity of 6 materials.
a) Which two metals have the lowest resistivities?
b) Are these materials often used as wires? Explain your answer.
c) Are these materials ever used as conductors? Explain your answer.
d) Which two metals have the highest resistivities?
e) What do you think these materials are used for? Explain your answer.
Worksheet: Series Circuits
1.
A series circuit has 4 resistors connected to a 120 V potential difference. The resistors have resistances of 15 , 45 , 60 , and
80 ?
a) Draw a picture of the circuit.
b) What is the total resistance of the circuit?
c) What is the total current flowing through the circuit?
d) Which resistor has the most current flowing through it? Explain your answer.
e) Which resistor creates the greatest drop in potential difference?
f) What is the V for this resistor?
g) How much power does the 45  resistor use?
A series circuit has 4 resistors connected to a 45.0 V potential difference. The resistors have resistances of 5.0 , 8.0 , 10.0 ,
and 12.0 ?
a) Draw a picture of the circuit.
b) What is the total resistance of the circuit?
c) What is the current flowing through the 8.0  resistor?
d) What is the drop in potential difference through the 10.0  resistor?
e) If another 5.0  resistor was connected in series, describe what would happen to the circuit’s:
i.
total resistance
ii.
total current
Worksheet: Parallel Circuits
2.
1. A parallel circuit has 4 resistors each on different paths connected to a 120 V potential difference. The resistors have resistances of
15 , 45 , 60 , and 80 ?
a) Draw a picture of the circuit.
b) What is the total resistance of the circuit?
c) What is the total current flowing through the circuit?
d) Which resistor has the most current flowing through it?
e) What is the current flowing through this resistor?
f) Which resistor creates the greatest drop in potential difference? Explain your answer.
g) How much power does the 45  resistor use?
2. A parallel circuit has 3 resistors each on different paths connected to a 120 V potential difference. The resistors have resistances of
5.0 , 7.5 , and 9.8 ?
a) Draw a picture of the circuit.
b) What is the current flowing through the 5.0  resistor?
c) What is the current flowing through the 7.5  resistor?
d)
e)
f)
g)
What is the current flowing through the 9.8  resistor?
What is the total current flowing through the circuit?
What is the total resistance of the circuit?
Did you notice the in problems #1 and #2 you found the total current and total resistance of the circuit two different ways? If
you did not, consider how in each problem you can work directly through the steps.
3. A parallel circuit has 4 resistors each on different paths connected to a 45.0 V potential difference. The resistors have resistances of
5.0 , 8.0 , 10.0 , and 12.0 ?
a) Draw a picture of the circuit.
b) What is the total resistance of the circuit?
c) What is the current flowing through the 8.0  resistor?
d) What is the drop in potential difference through the 10.0  resistor?
e) If another 5.0  resistor was connected on a separate parallel path, describe what would happen to the circuit’s:
i.
total resistance
ii.
total current
Worksheet: More Circuits
1.
a) How much current flows through the 20  resistor?
b) What is the drop in potential difference across the 15 resistor?
2.
a) What is the potential difference across the 5 resistor?
b) What is the current through the 8 resistor?
c) What is the total resistance in the circuit?
3.
a) What is the total resistance of the circuit?
b) What is the current through each of the resistors?
4. a) What is the total resistance of the circuit?
b) What is the current through each of the resistors?
c) What is the drop in potential difference across the 12 resistor?
You have only 4 resistors. Design a combination circuit that has a total resistance of 10 .
You have only 3 resistors. Design a combination circuit that has a total resistance of 2 .
You have only 5 resistors. Design a combination circuit that has a total resistance of 11.25 .
You have resistors of 5.0 , 7.0 , and 9.0 .
a) What is the greatest possible resistance you could create by connecting these resistors in a circuit?
b) What is the lowest possible resistance you could create by connecting these resistors in a circuit?
9. You want to use an ammeter to measure current. Should it:
a) be connected in Series or Parallel?
b) have a low resistance or high resistance?
c) Explain your two previous answers.
10. You want to use a voltmeter to measure potential difference. Should it:
a) be connected in Series or Parallel?
b) have a low resistance or high resistance?
c) Explain your two previous answers.
11. Three wires are connected at a single point. The currents of the three wires leading into the junction are 3 A, 6 A, and 7 A.
Leaving the junction, two of the wires have currents of 2 A and 10 A. What is the current traveling through the third wire after the
junction?
12. Three wires are connected at a single point. The currents of the three wires leading into the junction are 13 A, 26 A, and 17 A.
Leaving the junction, two of the wires have currents of 23 A and 13 A. What is the current traveling through the third wire after
the junction?
13. What law or rule best explains the answers to the previous two problems?
14. a) What is a short circuit?
b) Describe what happens in terms of V, I, and R when a short circuit occurs.
c) How do electricians prevent short circuits from doing more damage than they would if these safeguards were not employed?
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Worksheet: Power Problems
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7.
A hair dryer with a current of 2.0 A is connected to a 120 V potential difference.
a) How much resistance does the hair dryer have?
b) What is the power used by the hair dryer?
c) If the hair dryer is used for 2 minutes, how many Joules of energy are used?
A toaster with a resistance of 90.0  is connected to a 120V potential difference.
a) What is the power used by the toaster?
b) If the toaster is used for 5 minutes, how many Joules of energy are used?
c) How much current does the toaster draw?
d) If the toaster is used for 5 minutes, how many electrons pass through it?
A toy car has a maximum power of 23.0 W when it is hooked up to a 9.0 V battery.
a) How much current is the car drawing?
b) What is the resistance of the car?
c) If the car has a mass of 0.8 kg and starts from rest, how fast will it be going after moving for 1.3 seconds?
A 60 W light bulb is connected to a 120 V potential difference.
a) What is the current drawn by the bulb?
b) What is the resistance of the bulb?
The power company charges $0.07/kWh.
a) If you use 50 kWh in a day, how much will you be charged for that day?
b) If you turn your 9.0  toaster on for 1 minute with a 120 V circuit, how much will that cost?
How many joules are equivalent to 1kWh?
How many kWh are equivalent to 1 Joule?