Q1. One hertz is defined as
- A. one ampere per second.
- B. one cycle per second.
- C. one volt per second.
- D. one coulomb per second.
View Correct Answer
Answer: B
1 hertz is defined as 1 cycle per second. A 60-hertz electric current oscillates at 60 cycles per second.
Q2. One advantage of alternating current is that it is easy to
- A. store.
- B. convert into chemical energy.
- C. transport through wire.
- D. transmit through air.
View Correct Answer
Answer: C
Alternating current travels much further through wire than direct current.
Q3. Electric current can travel only through a
- A. wire.
- B. circuit.
- C. battery.
- D. load.
View Correct Answer
Answer: B
Without a circuit, electrons cannot travel, so there is no electric current.
Q4. Copper is used in most electric wires because it is
- A. a semiconductor.
- B. not likely to heat up during normal usage.
- C. a good resistor and inexpensive.
- D. a good conductor and inexpensive.
View Correct Answer
Answer: D
Copper is a good conductor and inexpensive. Choice B, while true, is not the whole answer, as it also applies, for example, to gold.
Q5. Amperes are a measure of
- A. the number of electrons moving through a conductor
- B. electrical pressure.
- C. a material’s ability to store electric current.
- D. the total resistance of a series circuit.
View Correct Answer
Answer: A
Amperes measure the number of electrons moving through a conductor.
Q6. Ohms are a measure of
- A. capacitance.
- B. resistance.
- C. current.
- D. cycles per second.
View Correct Answer
Answer: B Ohms are a measure of resistance.
Q7. If amperes = volts/ohms, then volts =
- A. 1/(amperes × ohms).
- B. ohms/amperes.
- C. amperes/ohms.
- D. amperes × ohms
View Correct Answer
Answer: D Using algebra, multiply both sides by ohms.
You should get volts = amperes × ohms.
Q8. A circuit with 20 amperes has a load of 12 ohms. What is the voltage?
- A. 60
- B. 120
- C. 240
- D. 24
View Correct Answer
Answer: C volts = amperes × ohms. = 20 × 12 =240.
Q9. If the resistance of a circuit is 0, the circuit is
- A. an open circuit.
- B. a short circuit.
- C. a superconductor circuit.
- D. a semiconductor circuit.
View Correct Answer
Answer: B
This circuit will have a dangerously high current and may burn up or cause a fire. It should trip a circuit breaker or blow a fuse before too
much damage occurs.
Q10. If a transformer raises the voltage, it will
- A. raise the resistance.
- B. reduce the resistance.
- C. raise the amperage.
- D. reduce the amperage.
View Correct Answer
Answer: D
The overall amount of power does not change. Power = amperes × volts. So if voltage rises, amperage must fall.
Q11. Which of these devices depends on the close relationship between electricity and magnetism?
- A. Transformer
- B. Electromagnet
- C. Electric motor
- D. All of the above
View Correct Answer
Answer: D
In a transformer, electricity is converted into magnetism and back into electricity. In an electromagnet, electricity is converted into magnetism. In an electric motor, electromagnets create a repulsive force that causes the rotor to spin.
Q12. If you are soldering two wires, you need solder,
- A. heat, and flux.
- B. and heat.
- C. and flux.
- D. flux, and electrical tape.
View Correct Answer
Answer: A
Heat alone will not do the job, because the wires will start to corrode when you heat them. The solder does not adhere to corrosion.
Q13. When connecting wires in the house, the bare copper wire is sometimes replaced by the
- A. the black wire.
- B. the white wire.
- C. the hot wire.
- D. conduit.
View Correct Answer
Answer: D
Conduit (either flexible or rigid) provides a safe return path for electricity in many wiring systems.
Q14. To hook up an electric heater, you need
- A. three supply wires.
- B. four supply wires.
- C. heavy supply wires.
- D. no supply wires.
View Correct Answer
Answer: C
Heaters use high current, which demands heavy wires.
Q15. In most home wiring, the hot wire is
- A. black.
- B. blue.
- C. green.
- D. white.
View Correct Answer
Answer: A
Black is the most common color for hot wires, although red and blue are sometimes used.
Q16. To control a light from each end of a hallway, you would install
- A. two single-pole switches.
- B. one four-way switch.
- C. one three-way switch.
- D. two three-way switches.
View Correct Answer
Answer: D
Three-way switches are used in pairs to control one light from two locations.
Q17. At 120 volts, a 15-ampere circuit will carry _______ power than a 20-ampere circuit.
- A. more
- B. less
- C. first less, then more
- D. first more, then less
View Correct Answer
Answer: B
Amperes = volts × power. Voltage does not change, so fewer amperes will carry less power.
Q18. To connect a battery properly, you must
- A. observe proper polarity.
- B. get the right voltage.
- C. both A and B.
- D. be certain the battery is chemical-free.
View Correct Answer
Answer: C
Both the polarity and the voltage must be correct for a battery to work right.
Q19. When you are making an electrical connection to a large battery,
- A. never tighten the terminal.
- B. tighten the terminal, then back off one turn.
- C. use salt water to prevent corrosion.
- D. tighten the terminal securely.
View Correct Answer
Answer: D
Loose electrical connections can cause fire or equipment damage. Choice C, saltwater, is wrong because it will cause corrosion, reducing
conductivity across the connection.
Q20. If you need to reduce the voltage in a certain part of a circuit, you could use a
- A. capacitor.
- B. transistor.
- C. resistor.
- D. inductor.
View Correct Answer
Answer: C
A resistor reduces voltage.
