Technician exam: electrical principles
Current, voltage, resistance, power, Ohm's law, decibels and metric prefixes. 50 questions, 10 at a time, starting with ones you haven't seen.
Rules to remember10 key electrical principles rulesShow the rules
- Kilo means one thousand, so one kilovolt is 1000 volts. (p. 37)
- Micro means one millionth, so a microvolt is one millionth of a volt. (p. 37)
- Milli means one thousandth, so 3000 milliamperes divided by 1000 is 3 amperes. (p. 37)
- One MHz is 1000 kHz, so 3.525 MHz times 1000 is 3525 kHz. (p. 37)
- A microfarad is one million picofarads, so 1,000,000 pF equals exactly 1 microfarad. (p. 37)
- Doubling power is an increase of about 3 dB, and going from 5 to 10 watts doubles the power. (p. 38)
- A tenfold increase in power is 10 dB, and 200 watts is ten times 20 watts. (p. 38)
- Using P = I x E, 10 amperes times 13.8 volts equals 138 watts. (p. 40)
- Ohm's law gives voltage as current times resistance, E = I x R. (p. 41)
- Using E = I x R, 0.5 amperes times 2 ohms is 1 volt. (p. 42)
Taken from the explanations to checked practice questions; page numbers link to the official handbook.
Sample electrical principles questions
1.What is the abbreviation for kilohertz?
- AKHz
- BKHZ
- CkHz
- Dkhz
Show the answer
✓ C. kHz
Kilohertz is written kHz: lowercase k for kilo and capital H for hertz, named after a person.
2.How much power is delivered by a voltage of 13.8 volts DC and a current of 10 amperes?
- A0.7 watts
- B138 watts
- C3.8 watts
- D23.8 watts
Show the answer
✓ B. 138 watts
Using P = I x E, 10 amperes times 13.8 volts equals 138 watts.
3.Electrical current is measured in which of the following units?
- AVolts
- BWatts
- CAmperes
- DOhms
Show the answer
✓ C. Amperes
Current, the rate of electron flow, is measured in amperes (amps).
4.Which is equal to one kilovolt?
- AOne thousand volts
- BOne million volts
- COne hundred volts
- DOne one-thousandth of a volt
Show the answer
✓ A. One thousand volts
Kilo means one thousand, so one kilovolt is 1000 volts.