Electronics quiz
Ohm's law & power quiz
V = IR, P = VI, and the quick calculations that come up on every board.
19 questions in the app. A few of them, with their answers:
Ohm's law is written as:
- V = I / R
- V = I × R ✓
- V = R / I
- I = V × R
Answer Ohm's law: voltage equals current multiplied by resistance (V = I × R).
A 12 V supply is connected across a 4 Ω resistor. What current flows?
- 0.33 A
- 3 A ✓
- 4.8 A
- 48 A
Answer I = V / R = 12 / 4 = 3 A.
A resistor carries 2 A and drops 10 V across it. What is its resistance?
- 5 Ω ✓
- 20 Ω
- 0.2 Ω
- 12 Ω
Answer R = V / I = 10 / 2 = 5 Ω.
Electrical power is calculated as:
- P = V / I
- P = V × I ✓
- P = I / V
- P = V − I
Answer Power equals voltage multiplied by current (P = V × I).
A component draws 0.5 A at 9 V. How much power does it dissipate?
- 18 W
- 4.5 W ✓
- 9.5 W
- 0.056 W
Answer P = V × I = 9 × 0.5 = 4.5 W.
