Physics MCQ Practice 30 — Science Foundation Course for Class 11 & 12

1. A body is thrown vertically upward with velocity 25 m/s. The maximum height reached (g=10 m/s²) is:

(a) 25 m (b) 31.25 m (c) 62.5 m (d) 12.5 m

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Correct Answer: (b) 31.25 m

Explanation:
H = u²/(2g) = 625 / 20 = 31.25 m

2. The acceleration due to gravity at height h = R (Earth radius) above surface is g/4. At depth d = R/2, g' is:

(a) g/2 (b) g/4 (c) g (d) Zero

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Correct Answer: (a) g/2

Explanation:
g' = g (1 - d/R) = g/2

3. The equivalent resistance when 3 Ω and 6 Ω are in parallel and that combination in series with 4 Ω is:

(a) 13 Ω (b) 6 Ω (c) 2 Ω (d) 7 Ω

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Correct Answer: (b) 6 Ω

Explanation:
Parallel = 2 Ω, total = 2 + 4 = 6 Ω

4. The frequency of a wave is 500 Hz. The time period is:

(a) 0.002 s (b) 0.02 s (c) 2 s (d) 500 s

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Correct Answer: (a) 0.002 s

Explanation:
T = 1/500 = 0.002 s

5. The magnetic field due to a long straight wire at distance r is proportional to:

(a) 1/r (b) 1/r² (c) r (d) r²

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Correct Answer: (a) 1/r

Explanation:
B = μ₀I / (2πr) ∝ 1/r

6. A convex lens of focal length 30 cm forms a real image at 90 cm. The object distance is:

(a) 45 cm (b) 22.5 cm (c) 60 cm (d) 15 cm

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Correct Answer: (a) 45 cm

Explanation:
1/v - 1/u = 1/f → u = -45 cm

7. The power factor in a purely inductive circuit is:

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

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Correct Answer: (b) 0

Explanation:
Pure inductive circuit has power factor 0

8. The particle with highest ionizing power is:

(a) Alpha (b) Beta (c) Gamma (d) Neutron

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Correct Answer: (a) Alpha

Explanation:
Alpha particles have the highest ionizing power

9. If the length of a simple pendulum is increased by 69%, the time period increases by approximately:

(a) 30% (b) 69% (c) 34.5% (d) 138%

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Correct Answer: (a) 30%

Explanation:
T ∝ √L → √1.69 ≈ 1.3 → 30% increase

10. The SI unit of electric field intensity is:

(a) N/C (b) V/m (c) Both (a) and (b) (d) J/C m

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Correct Answer: (c) Both (a) and (b)

Explanation:
E = F/q = N/C = V/m