Physics MCQs

Question #821

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Which instrument measures the speed of rotation of a shaft?

A. Speedometer

B. Anemometer

C. Tachometer

D. Odometer

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Correct Answer: Option C

Explanation:
Tachometer measures rotational speed (RPM). Speedometer vehicle speed. Odometer distance.

This question belongs to: Science Physics

Question #822

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The device used to view objects inside the body is

A. Microscope

B. Periscope

C. Endoscope

D. Telescope

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Correct Answer: Option C

Explanation:
Endoscope uses optical fibres for internal examination.

This question belongs to: Science Physics

Question #823

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The part of the refrigerator that absorbs heat from the interior is

A. Expansion valve

B. Evaporator coils

C. Condenser coils

D. Compressor

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Correct Answer: Option B

Explanation:
Evaporator (cooling coil) absorbs heat, refrigerant evaporates.

This question belongs to: Science Physics

Question #824

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The scientist who discovered the link between electricity and magnetism was

A. Maxwell

B. Faraday

C. Oersted

D. Coulomb

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Correct Answer: Option C

Explanation:
Oersted found that current-carrying wire deflects compass needle.

This question belongs to: Science Physics

Question #825

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The Nobel Prize in Physics 1901 was awarded to

A. Einstein

B. Röntgen

C. Planck

D. Curie

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Correct Answer: Option B

Explanation:
Wilhelm Röntgen for discovery of X-rays.

This question belongs to: Science Physics

Question #826

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The physical quantity having unit henry is

A. Inductance

B. Resistance

C. Conductance

D. Capacitance

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Correct Answer: Option A

Explanation:
Henry (H) = V·s/A = Ω·s.

This question belongs to: Science Physics

Question #827

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A body of mass 2 kg is raised to height 10 m and dropped. Potential energy just before dropping is (g=10)

A. 20 J

B. 200 J

C. 0 J

D. 100 J

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Correct Answer: Option B

Explanation:
PE = mgh = 2×10×10 = 200 J.

This question belongs to: Science Physics

Question #828

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The force acting on a particle of mass 1 kg moving in a circle of radius 0.5 m with speed 2 m/s is

A. 8 N

B. 1 N

C. 4 N

D. 2 N

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Correct Answer: Option A

Explanation:
Centripetal force = m v²/r = 1×4/0.5 = 8 N.

This question belongs to: Science Physics

Question #829

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The dimensional formula for work is

A. [ML²T⁻²]

B. [MLT⁻²]

C. [ML²T⁻¹]

D. [MLT⁻¹]

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Correct Answer: Option A

Explanation:
Work = Force × displacement = [MLT⁻²][L] = [ML²T⁻²].

This question belongs to: Science Physics

Question #830

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A car travels 30 m in 2 s with uniform acceleration starting from rest. Acceleration is

A. 7.5 m/s²

B. 15 m/s²

C. 3.75 m/s²

D. 30 m/s²

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Correct Answer: Option B

Explanation:
s = ½ a t² => 30 = ½ a (4) => a = 15 m/s².

This question belongs to: Science Physics

Question #831

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The velocity of a body changes from 2 m/s to 10 m/s in 4 s. Distance covered in this time is (assuming constant acceleration)

A. 32 m

B. 48 m

C. 24 m

D. 16 m

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Correct Answer: Option C

Explanation:
a = (10-2)/4 = 2 m/s². s = 2×4 + ½×2×16 = 8+16=24 m. Or average velocity 6 m/s ×4=24.

This question belongs to: Science Physics

Question #832

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The recoil of a gun when a bullet is fired is an example of

A. Law of gravitation

B. Newton's third law and conservation of momentum

C. Newton's second law

D. Newton's first law

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Correct Answer: Option B

Explanation:
Action-reaction and momentum conservation.

This question belongs to: Science Physics

Question #833

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A force of 5 N gives mass m1 acceleration 8 m/s² and mass m2 acceleration 24 m/s². What acceleration would it give if both masses tied together?

A. 6 m/s²

B. 4 m/s²

C. 16 m/s²

D. 32 m/s²

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Correct Answer: Option A

Explanation:
m1 = 5/8 = 0.625 kg, m2 = 5/24 ≈ 0.2083 kg. Total m=0.8333 kg. a = 5/0.8333 ≈ 6 m/s².

This question belongs to: Science Physics

Question #834

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The kinetic energy of a body becomes 4 times. Momentum becomes

A. 4 times

B. 16 times

C. Same

D. 2 times

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Correct Answer: Option D

Explanation:
p ∝ √K, so if K'=4K, p'=2p.

This question belongs to: Science Physics

Question #835

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A machine does 1000 J of work in 20 s. Power is

A. 20000 W

B. 50 W

C. 5 W

D. 20 W

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Correct Answer: Option B

Explanation:
P = 1000/20 = 50 W.

This question belongs to: Science Physics

Question #836

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The gravitational constant G has dimensions

A. [M⁻¹L³T⁻¹]

B. [ML²T⁻²]

C. [M⁻¹L³T⁻²]

D. [M⁻²L³T⁻²]

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Correct Answer: Option C

Explanation:
F = G m1 m2 / r² => G = F r² / (m1 m2) => [MLT⁻²][L²]/[M²] = [M⁻¹L³T⁻²].

This question belongs to: Science Physics

Question #837

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The weight of a body on a planet is 100 N. If planet's radius is half and density same as Earth, weight becomes

A. 25 N

B. 100 N

C. 50 N

D. 200 N

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Correct Answer: Option C

Explanation:
g = GM/R² = G (ρ 4/3 π R³)/R² ∝ ρ R. If radius half, density same, g becomes half. Weight half = 50 N.

This question belongs to: Science Physics

Question #838

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A man in a lift feels heavier when lift

A. Accelerates upward

B. Moves upward with constant velocity

C. Moves downward with constant velocity

D. Accelerates downward

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Correct Answer: Option A

Explanation:
Apparent weight = m(g+a) > mg when accelerating upward.

This question belongs to: Science Physics

Question #839

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The pressure at the bottom of a tank of water of depth 10 m (ρ=1000, g=10) is

A. 10 Pa

B. 100000 Pa

C. 100 Pa

D. 1000 Pa

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Correct Answer: Option B

Explanation:
P = ρgh = 1000×10×10 = 100,000 Pa = 100 kPa.

This question belongs to: Science Physics

Question #840

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A wooden block floats with half its volume submerged in water. Density of wood is

A. 1 g/cm³

B. 2 g/cm³

C. 0.5 g/cm³

D. 0.25 g/cm³

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Correct Answer: Option C

Explanation:
ρ_wood V g = ρ_water (V/2) g => ρ_wood = 0.5 ρ_water = 0.5 g/cm³.

This question belongs to: Science Physics

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