NSAA NSAA Physics - Electricity and Magnetism 2 — Questions and Answers
Question 1: A 10 Ω resistor carries 2 A of current. What power is dissipated?
- 5 W
- 20 W
- 40 W (Correct answer)
- 100 W
Correct answer: 40 W
Power P = I²R = 4 × 10 = 40 W.
Question 2: A capacitor stores 0.01 C of charge at a potential difference of 5 V. What is its capacitance?
- 0.002 F (Correct answer)
- 0.005 F
- 0.02 F
- 0.05 F
Correct answer: 0.002 F
Capacitance C = Q/V = 0.01/5 = 0.002 F.
Question 3: Which of the following best describes the direction of conventional current in a circuit?
- From negative to positive terminal
- From positive to negative terminal (Correct answer)
- In both directions simultaneously
- From the lowest potential to highest potential
Correct answer: From positive to negative terminal
By convention, current flows from the positive terminal of the source, through the circuit, to the negative terminal.
Question 4: A solenoid with 200 turns carries a current. Doubling the number of turns while keeping current constant will have what effect on the magnetic field inside?
- Halve it
- Keep it the same
- Double it (Correct answer)
- Quadruple it
Correct answer: Double it
The magnetic field inside a solenoid is B = μ₀nI, proportional to the number of turns per unit length, so doubling turns doubles B.
Question 5: A wire of length 0.5 m carrying 4 A is placed perpendicular to a magnetic field of 0.3 T. What force acts on it?
- 0.3 N
- 0.6 N (Correct answer)
- 1.2 N
- 2.4 N
Correct answer: 0.6 N
F = BIL = 0.3 × 4 × 0.5 = 0.6 N.
Question 6: Which law states that the induced EMF in a circuit is proportional to the rate of change of magnetic flux?
- Ampere's Law
- Coulomb's Law
- Faraday's Law (Correct answer)
- Lenz's Law
Correct answer: Faraday's Law
Faraday's Law of electromagnetic induction states that EMF = -dΦ/dt.
NSAA NSAA Physics - Electricity and Magnetism 2
A 10 Ω resistor carries 2 A of current.
What power is dissipated?