Physics MCQ Practice 24 — Science Foundation Course for Class 11 & 12

1. A body starts from rest and moves with uniform acceleration. The distance covered in the first 4 seconds is 32 m. The acceleration is:

(a) 2 m/s² (b) 4 m/s² (c) 8 m/s² (d) 16 m/s²

Show Answer & Explanation

Correct Answer: (b) 4 m/s²

Explanation:
s = ½at² → 32 = ½a×16 → a = 4 m/s²

2. The escape velocity on a planet is 5 km/s. If the planet's mass is doubled and radius halved, the new escape velocity is:

(a) 5 km/s (b) 10 km/s (c) 7.07 km/s (d) 2.5 km/s

Show Answer & Explanation

Correct Answer: (b) 10 km/s

Explanation:
v_esc ∝ √(M/R) → √(2M / (R/2)) = √4 = 2 times = 10 km/s

3. Three capacitors of 2 μF, 3 μF and 6 μF in series. Equivalent capacitance is:

(a) 11 μF (b) 1 μF (c) 2 μF (d) 6 μF

Show Answer & Explanation

Correct Answer: (b) 1 μF

Explanation:
1/C = 1/2 + 1/3 + 1/6 = 1 → C = 1 μF

4. The frequency of a wave is 50 Hz. The time period is:

(a) 0.02 s (b) 0.2 s (c) 2 s (d) 20 s

Show Answer & Explanation

Correct Answer: (a) 0.02 s

Explanation:
T = 1/f = 1/50 = 0.02 s

5. The force on a current-carrying wire in a magnetic field is zero when the current is:

(a) Parallel to B (b) Perpendicular to B (c) At 45° (d) Zero

Show Answer & Explanation

Correct Answer: (a) Parallel to B

Explanation:
F = I l B sinθ = 0 when θ = 0° or 180°

6. A convex lens of focal length 20 cm forms a real image at 40 cm. The object distance is:

(a) 40 cm (b) 13.3 cm (c) 26.7 cm (d) 30 cm

Show Answer & Explanation

Correct Answer: (a) 40 cm

Explanation:
1/v - 1/u = 1/f → 1/40 - 1/u = 1/20 → u = -40 cm

7. The power factor in a circuit containing only inductance is:

(a) 1 (b) 0 (c) 0.5 (d) Infinite

Show Answer & Explanation

Correct Answer: (b) 0

Explanation:
Pure inductive circuit has power factor 0

8. The control rods in a nuclear reactor are used to absorb:

(a) Neutrons (b) Protons (c) Electrons (d) Gamma rays

Show Answer & Explanation

Correct Answer: (a) Neutrons

Explanation:
Control rods absorb neutrons to control the chain reaction

9. If the length of a simple pendulum is increased by 44%, the percentage increase in time period is approximately:

(a) 20% (b) 22% (c) 44% (d) 10%

Show Answer & Explanation

Correct Answer: (a) 20%

Explanation:
T ∝ √L → 44% increase in L → ~22% increase in T (approximately 20%)

10. The physical quantity with unit joule per second is:

(a) Energy (b) Power (c) Force (d) Momentum

Show Answer & Explanation

Correct Answer: (b) Power

Explanation:
Power = work/time = J/s = Watt