Physics MCQ Practice 29 — Science Foundation Course for Class 11 & 12

1. A ball is thrown upward with velocity 20 m/s. The time taken to reach the highest point (g=10 m/s²) is:

(a) 1 s (b) 2 s (c) 4 s (d) 5 s

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Correct Answer: (b) 2 s

Explanation:
v = u - gt → 0 = 20 - 10t → t = 2 s

2. The acceleration due to gravity at height h = R (Earth radius) is g/4. The value of g at depth d = R/2 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 4 Ω and 12 Ω in parallel is:

(a) 16 Ω (b) 3 Ω (c) 8 Ω (d) 2 Ω

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Correct Answer: (b) 3 Ω

Explanation:
1/R = 1/4 + 1/12 = 1/3 → R = 3 Ω

4. The frequency of a wave is 200 Hz. The time period is:

(a) 0.005 s (b) 0.05 s (c) 5 s (d) 200 s

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Correct Answer: (a) 0.005 s

Explanation:
T = 1/200 = 0.005 s

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

(a) r (b) r² (c) r³ (d) r⁰

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Correct Answer: (a) r

Explanation:
B ∝ 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 of a circuit with only capacitance is:

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

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Correct Answer: (b) 0

Explanation:
Pure capacitive circuit has power factor 0

8. The particle emitted in beta decay is:

(a) Helium nucleus (b) Electron (c) Neutron (d) Proton

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Correct Answer: (b) Electron

Explanation:
Beta particle is an electron (or positron)

9. If the length of a simple pendulum is increased by 21%, the time period increases by approximately:

(a) 10% (b) 21% (c) 10.5% (d) 42%

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Correct Answer: (c) 10.5%

Explanation:
T ∝ √L → 21% increase in L → 10.5% increase in T

10. The SI unit of magnetic field strength H is:

(a) Tesla (b) Ampere per metre (c) Weber (d) Gauss

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Correct Answer: (b) Ampere per metre

Explanation:
H is measured in A/m