Physics MCQs

Question #441

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Which of the following particles has the largest penetrating power?

A. Gamma rays

B. Alpha particles

C. Protons

D. Beta particles

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Correct Answer: Option A

Explanation:
Gamma rays (photons) have highest penetration, stopped by thick lead/concrete. Alpha least (paper/skin). Beta intermediate (aluminium). Neutrons also penetrating but not listed. Gamma has no charge.

This question belongs to: Science Physics

Question #442

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The principle of working of a hydrogen bomb is

A. Nuclear fusion

B. Chain reaction

C. Chemical explosion

D. Nuclear fission

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Correct Answer: Option A

Explanation:
Hydrogen bomb uses uncontrolled fusion of deuterium and tritium triggered by fission bomb. Releases vast energy, thermonuclear reaction. Sun's energy is fusion.

This question belongs to: Science Physics

Question #443

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A real image can be obtained on a screen. Which of the following always forms a virtual image?

A. Concave mirror

B. Concave lens

C. Convex lens

D. Convex mirror

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Correct Answer: Option D

Explanation:
Convex mirror and concave lens always produce virtual images. Concave mirror and convex lens can produce real images under certain conditions. So convex mirror always virtual.

This question belongs to: Science Physics

Question #444

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The electrical resistance of a conductor depends on its

A. Magnetic property

B. Length and area of cross-section

C. Transparency

D. Colour

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Correct Answer: Option B

Explanation:
R = ρL/A, depends on length (L), cross-sectional area (A), and resistivity (ρ) which depends on material and temperature. Not on colour or transparency.

This question belongs to: Science Physics

Question #445

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An object of mass 1 kg is moving with a velocity of 10 m/s. Its de Broglie wavelength is (h = 6.63×10⁻³⁴ Js)

A. 6.63 × 10⁻³⁵ m

B. 6.63 × 10⁻³⁶ m

C. 6.63 × 10⁻³⁴ m

D. 6.63 × 10⁻³³ m

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Correct Answer: Option A

Explanation:
λ = h/(mv) = 6.63×10⁻³⁴/(1×10) = 6.63×10⁻³⁵ m. Extremely small, not observable. For electron it's significant. de Broglie hypothesis: matter waves. This is modern physics.

This question belongs to: Science Physics

Question #446

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The instrument used to measure the humidity of air is

A. Barometer

B. Hygrometer

C. Anemometer

D. Hydrometer

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Correct Answer: Option B

Explanation:
Hygrometer measures relative humidity. Wet and dry bulb, hair hygrometer. Hydrometer measures liquid density. Anemometer wind speed. Barometer pressure.

This question belongs to: Science Physics

Question #447

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Which of the following is not a transverse wave?

A. Wave on a string

B. Radio wave

C. Light wave

D. Sound wave in air

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Correct Answer: Option D

Explanation:
Sound in air is longitudinal. Light, radio are EM waves, transverse. Wave on string transverse. Water waves combine transverse and longitudinal.

This question belongs to: Science Physics

Question #448

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The power of a lens is measured in

A. Dioptre

B. Lux

C. Metre

D. Watt

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Correct Answer: Option A

Explanation:
Dioptre (D) = m⁻¹. Power = 1/f in metres. Convex positive, concave negative. Optometry uses dioptre.

This question belongs to: Science Physics

Question #449

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The value of g at the centre of Earth is

A. 4.9 m/s²

B. 9.8 m/s²

C. Zero

D. Infinite

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Correct Answer: Option C

Explanation:
g decreases with depth: g' = g(1 - d/R). At centre d=R, g'=0. Weightless at centre. At poles g=9.83, equator 9.78. At surface it's maximum.

This question belongs to: Science Physics

Question #450

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The phenomenon of splitting of white light into its constituent colours is called

A. Scattering

B. Refraction

C. Polarisation

D. Dispersion

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Correct Answer: Option D

Explanation:
Dispersion happens because refractive index varies with wavelength. Prism, rainbow. Scattering is Tyndall effect (blue sky). Polarisation restricts vibrations.

This question belongs to: Science Physics

Question #451

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The unit of inductance is

A. Ohm

B. Coulomb

C. Farad

D. Henry

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Correct Answer: Option D

Explanation:
Henry (H) = V·s/A = Ω·s. Self-inductance unit. Capacitance unit farad. Ohm resistance. Coulomb charge.

This question belongs to: Science Physics

Question #452

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A stone is thrown vertically upward with velocity 49 m/s. The time after which it returns to thrower is (g=9.8)

A. 5 s

B. 2.5 s

C. 15 s

D. 10 s

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Correct Answer: Option D

Explanation:
Time of flight T = 2u/g = 2×49/9.8 = 98/9.8 = 10 s. Up and down symmetric. Max height = u²/(2g) = 122.5 m.

This question belongs to: Science Physics

Question #453

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The instrument used to view distant objects is

A. Endoscope

B. Telescope

C. Microscope

D. Periscope

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Correct Answer: Option B

Explanation:
Telescope (refracting/reflecting) makes distant objects appear nearer, magnified. Microscope for tiny near objects. Periscope uses mirrors to see over obstacles. Endoscope medical.

This question belongs to: Science Physics

Question #454

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The speed of light in vacuum is

A. 3 × 10¹⁰ m/s

B. 3 × 10⁴ m/s

C. 3 × 10⁶ m/s

D. 3 × 10⁸ m/s

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Correct Answer: Option D

Explanation:
c = 2.9979 × 10⁸ m/s, commonly 3×10⁸ m/s. In glass slower. It's a universal constant, maximum speed. Used in relativity, E=mc².

This question belongs to: Science Physics

Question #455

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The force that keeps a body moving in a circular path is called

A. Frictional force

B. Centrifugal force

C. Centripetal force

D. Gravitational force

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Correct Answer: Option C

Explanation:
Centripetal force acts towards centre, necessary for circular motion. Centrifugal is pseudo-force in rotating frame. In uniform circular motion, centripetal force = mv²/r.

This question belongs to: Science Physics

Question #456

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A 10 kg object is falling freely under gravity. The net force acting on it is (g=10)

A. 0 N

B. 10 N

C. 1 N

D. 100 N

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Correct Answer: Option D

Explanation:
Weight = mg = 10×10 = 100 N. In free fall, only force is gravity (air resistance neglected). Net force = weight, so F = 100 N, causing acceleration g.

This question belongs to: Science Physics

Question #457

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The sound of thunder is heard after the flash of lightning because

A. Sound travels faster than light

B. Both travel at same speed

C. Light travels slower than sound

D. Light travels much faster than sound

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Correct Answer: Option D

Explanation:
Speed of light ≈ 3×10⁸ m/s, sound ≈ 340 m/s. Light reaches almost instantly, sound takes time. So thunder heard after lightning. Time delay gives distance: d = v_sound × t.

This question belongs to: Science Physics

Question #458

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The resistance of a wire is R. If its length is doubled and area is halved, the new resistance is

A. R/2

B. 4R

C. 2R

D. R

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Correct Answer: Option B

Explanation:
R ∝ L/A. New L'=2L, A'=A/2 => R' = ρ(2L)/(A/2) = 4ρL/A = 4R. Alternatively, volume constant? Not given, here both changed independently. So 4R.

This question belongs to: Science Physics

Question #459

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The scientist who discovered the nucleus of an atom is

A. James Chadwick

B. Niels Bohr

C. J.J. Thomson

D. Ernest Rutherford

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Correct Answer: Option D

Explanation:
Rutherford's gold foil experiment (1911) revealed tiny, dense, positively charged nucleus. Thomson discovered electron, proposed plum-pudding. Chadwick discovered neutron. Bohr explained atomic spectra.

This question belongs to: Science Physics

Question #460

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The process of coating iron with zinc to prevent rusting is called

A. Annealing

B. Galvanisation

C. Alloying

D. Electroplating

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Correct Answer: Option B

Explanation:
Galvanisation: iron/steel coated with zinc to prevent corrosion. Zinc acts as sacrificial anode. Electroplating deposits metal layer using electricity. Alloying mixing metals. Annealing heat treatment.

This question belongs to: Science Physics

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