Physics MCQ Practice 18 — Science Foundation Course for Class 11 & 12

1. A train accelerates from rest to 20 m/s in 10 seconds. The distance covered is:

(a) 50 m (b) 100 m (c) 200 m (d) 400 m

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Correct Answer: (b) 100 m

Explanation:
s = ut + ½at², a = 2 m/s² → s = ½×2×100 = 100 m

2. The acceleration due to gravity at height h = R (Earth radius) above surface is:

(a) g/4 (b) g/2 (c) g/9 (d) g

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Correct Answer: (a) g/4

Explanation:
g' = g / (1 + h/R)² = g / (2) ² = g/4

3. Three resistors of 4 Ω each are connected in delta. The equivalent resistance between any two terminals is:

(a) 12 Ω (b) 6 Ω (c) 2 Ω (d) 8 Ω

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Correct Answer: (c) 2 Ω

Explanation:
For delta connection, R_eq between two terminals is 2 Ω

4. The speed of sound in a gas is v. If temperature is increased to 4 times, the speed becomes:

(a) v (b) 2v (c) 4v (d) √2 v

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Correct Answer: (b) 2v

Explanation:
v ∝ √T → T ×4 → v ×2

5. The magnetic field inside a toroid is:

(a) Zero (b) μ₀NI/2πr (c) μ₀NI/2r (d) μ₀N I / r

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Correct Answer: (b) μ₀NI/2πr

Explanation:
B = μ₀ N I / (2πr)

6. A concave mirror of focal length 30 cm forms an image at 60 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 = -60 / (-30) = -2

7. The power factor of a series LCR circuit at resonance is:

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

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Correct Answer: (c) 1

Explanation:
At resonance, circuit is purely resistive → power factor = 1

8. The binding energy per nucleon is maximum for:

(a) Deuterium (b) Helium (c) Iron (d) Uranium

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Correct Answer: (c) Iron

Explanation:
Iron has the highest binding energy per nucleon

9. If the radius of a soap bubble is doubled, the excess pressure becomes:

(a) Same (b) Half (c) One-fourth (d) Double

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Correct Answer: (c) One-fourth

Explanation:
Excess pressure = 4T/r → r doubled → pressure 1/4

10. The SI unit of inductance is:

(a) Henry (b) Weber (c) Tesla (d) Ohm

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Correct Answer: (a) Henry

Explanation:
Unit of self-inductance L is Henry (H)