NSAA NSAA Physics - Electricity and Magnetism 1 — Questions and Answers
Question 1: A resistor has a voltage of 12 V across it and a current of 3 A through it. What is its resistance?
- 2 Ω
- 3 Ω
- 4 Ω (Correct answer)
- 36 Ω
Correct answer: 4 Ω
Using Ohm's Law: R = V/I = 12/3 = 4 Ω.
Question 2: Three resistors of 2 Ω, 3 Ω, and 5 Ω are connected in series. What is the total resistance?
- 1 Ω
- 5 Ω
- 10 Ω (Correct answer)
- 30 Ω
Correct answer: 10 Ω
In series, total resistance = 2 + 3 + 5 = 10 Ω.
Question 3: Two resistors of 6 Ω and 3 Ω are connected in parallel. What is the combined resistance?
- 1 Ω
- 2 Ω (Correct answer)
- 9 Ω
- 18 Ω
Correct answer: 2 Ω
1/R = 1/6 + 1/3 = 1/6 + 2/6 = 3/6 = 1/2, so R = 2 Ω.
Question 4: A charge of 4 C passes through a wire in 2 seconds. What is the electric current?
- 0.5 A
- 1 A
- 2 A (Correct answer)
- 8 A
Correct answer: 2 A
Current I = Q/t = 4/2 = 2 A.
Question 5: A 60 W bulb runs on a 120 V supply. What current does it draw?
- 0.25 A
- 0.5 A (Correct answer)
- 2 A
- 7200 A
Correct answer: 0.5 A
Current I = P/V = 60/120 = 0.5 A.
Question 6: What happens to the resistance of a metallic conductor as its temperature increases?
- Decreases
- Remains constant
- Increases (Correct answer)
- Drops to zero
Correct answer: Increases
In metallic conductors, higher temperature increases lattice vibrations, increasing resistance.
NSAA NSAA Physics - Electricity and Magnetism 1
A resistor has a voltage of 12 V across it and a current of 3 A through it.
What is its resistance?