Assignment Chapters 4 and 5

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