Electricity and Electric Circuits Review

You have your last midterm test next Friday, May 15. This test will cover electricity, electric circuits, quantum mechanics, and nuclear physics. It will be a longer test than usual. Today and tomorrow, you have time in class to get started on the review problems for the electricity and electric circuits part of the test.

Chapter 34 review problems

10. What is electric resistance?
11. Is electric resistance greater in a short fat wire or in a long thin wire?
22. From where do the electrons originate that flow in a typical electric circuit?
23. What is power?
28. Calculate the current in a toaster that has a heating element of 14 ohms when connected to a 120-V outlet.
36. Why are think wires rather than thin wires used to carry large currents?
48. Use the relationship power = current x voltage to find out how much current is drawn by a 120-watt hair dryer when it operates on 120 volts. Then use Ohm’s Law to find the resistance of the hair dryer.

Chapter 35 Review Problems

4. If three lamps are connected in series to a 6 volt battery, how many volts are impressed across each lamp?
6. If three lamps are connected in parallel to a 6 volt battery, how many volts are impressed across each lamp?
9. What happens to the total circuit resistance when more devices are added to a series circuit? To a parallel circuit?
10. What is the equivalent resistance of a pair of 8-ohm resistors in series? In parallel?
16. Calculate the current in a 48-V battery that powers a pair of 30-ohm resistors connected in series.
17. Calculate the current in a 48-V battery that powers a pair of 30-ohm resistors connected in parallel.
20. Why are household appliances almost never connected in series?
28. A 16-ohm loudspeaker and an 8-ohm loudspeaker are connected in parallel across the terminals of an amplifier. Assuming the speakers behave as resistors, calculate the equivalent resistance of the two speakers.
29. This uses a picture. See book.
30. How many 4 ohm resistors must be connected in parallel to create an equivalent resistance of 0.5 ohms?
31. This uses a picture. See book.
33. A 4-watt night light is plugged into a 120-volt circuit and operates continuously for a 31-day month.
a. How much current does it draw?
b. What is the resistance of its filament?
c. How much energy does it use in the month?
d. What is the cost of its operation for the month at the utility rate of 10 cents per kilowatt-hour?