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Power from voltage and current

Aviation Mechanic General (AMG) practice question 22 of 41 on Fundamentals of Electricity and Electronics. ACS element AM.I.A.K13 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONA DC circuit operates at 24 volts and draws 2 amperes. How much power is dissipated in the circuit?

  1. A12 watts, found by dividing volts by amperes
  2. B96 watts
  3. C48 watts
Show the answer and explanation

Correct answer: C. 48 watts

  • A — incorrect Dividing voltage by current gives resistance in ohms, not power; power is the product of current and voltage.
  • B — incorrect This doubles the correct product; power is simply I x E, which is 48 watts here.
  • C — correct The general power formula is P = I x E; 2 amperes x 24 volts = 48 watts.

BACKGROUND

Power is the rate of energy consumption or conversion, measured in watts, where one watt is one joule per second. For a simple DC circuit the general power formula is P = I x E, power equals current times voltage. The handbook example with a known voltage of 24 volts and current of 2 amperes gives 48 watts. Substituting Ohm's Law produces two other forms, P = I squared x R and P = E squared / R, so power can be found from any two of the three circuit quantities.

STUDY TIP

Memorize P = IE first; the I-squared-R and E-squared-over-R forms are just Ohm's Law substituted into it.

KEY POINTS

  • P = I x E for a DC circuit.
  • 24 volts x 2 amperes = 48 watts.
  • Alternate forms: P = I squared R and P = E squared / R.

SOURCES

  • FAA-H-8083-30B ch12 "Power Formulas Used in the Study of Electricity" (24 V, 2 A example)
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.