Electric Current and Circuits

Please solve the following problems. You must show all work. 

1) How long would it take for a net charge of 2.5 C to pass a location in a wire if it is to carry a steady current of 5.0 mA?

2) Two copper wires have equal lengths, but the diameter of one is three times that of the other.

a) The resistance of the thinner wire is _____ times that of the thicker wire: (Prove your work)

1) 3
2) 1/3
3) 9
4) 1/4

b) If a thicker wire has a resistance of 1.0 , what is the resistance of the thinner wire?

3) A 200 – W computer power supply is on 10 hours per day. If the cost of electricity is $0.15/kWh, what is the cost (to the nearest dollar) to run the computer every day for a year (365 days)?

4) What is the emf of a battery with an internal resistance of 0.15  if the battery delivers 1.5 A to an externally connected 5.0  resistors?

5) Three resistors of value 1.0 , 2.0  and 4.0  are connected in a parallel circuit with a 6.0 V battery.

a) What is the total equivalent resistance?
b) What is the voltage across and the current through each resistor?
c) The power delivered to the 4.0  resistor?

6) What is the equivalent capacitance of two capacitors of 0.40 F and 0.60 F when they are connected in:

a) series?
b) parallel?

7) Three capacitors of equal capacitance are connected in parallel to a battery, and together they draw a certain amount of charge Q from that battery.

a) Will the charge on each capacitor be

1) Q
2) 3Q
3) Q/3?

b) Three capacitors of 0.25 F each in parallel connected to a 12- V battery. What is the charge on each capacitor?

c) How much charge is drawn from the battery?