# Solve problems involving Ohm’s Law and electric circuits

Please solve the following problems. **You must show all work for full/partial credit.** When complete, attach a typed cover sheet and submit to the assignment drop-box.

**Question 1 (17 points): **

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?

**Question 2 (18 points): **

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

- The resistance of the thinner wire is ____ times that of the thicker wire: (prove your work)
- 3
- ⅓
- 9
- ¼

- If the t wire has a resistance of 1.0 Ω, what is the resistance of the thinner wire?

**Question 3 (17 points)**

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)?

**Question 4 (5 points)**

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

**Question 5 (16 points)**

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

- What is the total equivalent resistance?
- What is the voltage across each resistor?
- The power delivered to the 4.0 Ω resistor?

**Question 6 (10 points)**

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

- Series?
- Parallel?

**Question 7 (17 points)**

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.

- Will the charge on each capacitor be:
- Q
- 3Q
- Q/3

- Three capacitors of 0.25 µF in each parallel connected to a 12-V battery. What is the charge on each capacitor?
- How much charge is drawn from the battery?