Physics MCQ Practice 27 — Science Foundation Course for Class 11 & 12

1. A body starts from rest and covers 200 m in 10 seconds with uniform acceleration. The acceleration is:

(a) 2 m/s² (b) 4 m/s ² (c) 8 m/s² (d) 20 m/s²

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Correct Answer: (b) 4 m/s²

Explanation:
s = ½at ² → 200 = ½a×100 → a = 4 m/s²

2. The value of g at a depth d = R/2 below Earth's surface 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 of three 6 Ω resistors in parallel is:

(a) 18 Ω (b) 2 Ω (c) 6 Ω (d) 1 Ω

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Correct Answer: (b) 2 Ω

Explanation:
1/R = 3/6 = 0.5 → R = 2 Ω

4. The wavelength of a sound wave with frequency 680 Hz (v = 340 m/s) is:

(a) 0.5 m (b) 1 m (c) 2 m (d) 0.25 m

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Correct Answer: (a) 0.5 m

Explanation:
λ = v/f = 340 / 680 = 0.5 m

5. The magnetic field at the centre of a circular loop with current I and radius r is:

(a) μ₀I / (2r) (b) μ₀I / (2πr) (c) μ₀I / r (d) μ₀I / (4πr)

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Correct Answer: (a) μ₀I / (2r)

Explanation:
B = μ₀ I / (2r)

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

(a) -2 (b) +2 (c) -1 (d) +0.5

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Correct Answer: (a) -2

Explanation:
m = -v/u = -40 / (-20) = -2

7. The power factor of a circuit with R = 3 Ω, X_L = 4 Ω, X_C = 4 Ω is:

(a) 0.6 (b) 1 (c) 0.8 (d) 0

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Correct Answer: (b) 1

Explanation:
At resonance (X_L = X_C), power factor = 1

8. The energy source in the Sun is:

(a) Nuclear fission (b) Nuclear fusion (c) Chemical burning (d) Gravitational collapse

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Correct Answer: (b) Nuclear fusion

Explanation:
Hydrogen fusion into helium

9. If the length of a simple pendulum is increased by 100%, the time period increases by:

(a) 100% (b) 41% (c) 50% (d) 200%

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Correct Answer: (b) 41%

Explanation:
L doubled → T increases by √2 - 1 ≈ 41%

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