1. A Van de Graaff generator has 3.86 X 1014 excess electrons on it. A student walks by and
discharges the generator in a time of 0.050 s. What was the current? (3 marks)
2. A spark from a Van de Graaff generator transfers 3.8 X 103 J of electrical energy through a
potential difference of 2.50 X 104 V. Calculate the number of electrons which moved through
the spark. (3 marks)
3. A capacitor has 5.3 X 107 J of energy stored in it. The electric potential difference across the
capacitor is 4.3 X 103 V. If it takes 3.2 X 10-2 s to discharge the capacitor, what current must
flow? (3 marks)
4. For the circuit shown, calculate all the unknowns. (5 marks)
5. A food processor has a current of 6.3 A flowing through it. If the processor is drawing current
from a 110.0 V supply, what is the resistance of the food processor? (2 marks)
6. The resistance of an electronic element is 12.75 W. The length of the element is 3.2 m and it is
cylindrical in shape. The diameter of the device is 0.00100 m. What is the resistivity of this
element (a wire)? (3 marks)
7. For the following circuits, find the unknowns.
8.
The above circuit is simplified by replacing R2 and R3 with R7 in the following circuit. Also,
R4, R5, and R6 are replaced by R8 in the following circuit.
What is the value of R2, R3, R4, R5, and R6 given the following relationships? R2 = 2(R3),
R4 = 3(R5), R6 = 0.5(R5). (5 marks)
9. An appliance uses 120 V current and has a power rating of 250 W. What is the resistance of
the appliance, and what current does It use? (4 marks)
10. A person goes away on holidays and sets a 40 watt light bulb to turn on from 8:00 P.M. until
10:30 P.M. each day. The cost of electricity Is $0.037/kWh. If the person is away for
17 days, what did it cost our happy holidayer? (3 marks)
January, 6, 2014