SkyDrill

Effect of doubling voltage at constant resistance

Aviation Mechanic General (AMG) practice question 29 of 41 on Fundamentals of Electricity and Electronics. ACS element AM.I.A.K7 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONThe voltage across a resistor is doubled while its resistance stays constant. According to Ohm's Law, what happens to the current through the resistor?

  1. AIt doubles
  2. BIt is reduced to one-half
  3. CIt stays the same, since resistance is unchanged
Show the answer and explanation

Correct answer: A. It doubles

  • A — correct Ohm's Law is a linear relationship: with resistance constant, if the voltage across a resistor is doubled, the current through it doubles.
  • B — incorrect Current is halved when resistance is doubled at constant voltage, not when voltage is doubled.
  • C — incorrect Constant resistance does not fix the current; current is proportional to the applied voltage, so it changes with voltage.

BACKGROUND

Ohm's Law relates voltage, current, and resistance: I = E/R. The relationship is linear, meaning that if one quantity increases or decreases by a certain percentage, the related quantity changes by the same percentage. The handbook gives the example that doubling the voltage across a resistor doubles the current through it, provided the resistance remains constant. The handbook's worked example of this relationship uses a constant 20-ohm resistance: 10 volts gives 0.5 ampere, 60 volts gives 3 amperes, and 120 volts gives 6 amperes.

STUDY TIP

Think of Ohm's Law as a straight-line relationship: at fixed resistance, current rises in direct proportion to voltage.

KEY POINTS

  • I = E/R; the relationship is linear.
  • Doubling voltage at constant resistance doubles current.
  • Doubling resistance at constant voltage halves current.

SOURCES

  • FAA-H-8083-30B ch12 "Ohm's Law (Resistance)"
Practice the Aviation Mechanic General (AMG) test →Timed 60-question exam, by ACS area, or review your misses. Free.
MORE ON FUNDAMENTALS OF ELECTRICITY AND ELECTRONICS

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.