Physics MCQs

Question #1041

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Polarization proves light is:

A. Matter wave

B. Longitudinal wave

C. Mechanical wave

D. Transverse wave

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Correct Answer: Option D

Explanation:
Polarization possible only for transverse waves (oscillations ⊥ propagation). Longitudinal waves (sound) cannot be polarized. Memory aid: 'Polarization ⇒ transverse nature; light is EM transverse wave'. Wave property frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1042

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Pendulum on planet with g' = 4g. Period becomes:

A. Double

B. Half

C. Same

D. Four times

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Correct Answer: Option B

Explanation:
T ∝ 1/√g. If g' = 4g, T' = T/√4 = T/2. Higher gravity ⇒ faster oscillations. Memory aid: 'Pendulum: T ∝ 1/√g; 4× gravity ⇒ half period'. Oscillations proportionality frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1043

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Coil center magnetic field B = μ₀NI/(2R). If N doubled, B becomes:

A. Double

B. Four times

C. Same

D. Half

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Correct Answer: Option A

Explanation:
B ∝ N. Double turns ⇒ double field at center. Direct proportionality from Biot-Savart law. Memory tip: 'Coil field: B ∝ NI; more turns ⇒ stronger field'. Magnetism formula frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1044

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Heat transfer by fluid motion is:

A. All three

B. Convection

C. Radiation

D. Conduction

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Correct Answer: Option B

Explanation:
Convection: bulk fluid motion carries heat (natural: density-driven; forced: pump/fan). Conduction: molecular collisions; radiation: EM waves. Memory aid: 'Convection = fluid flow + heat; e.g., boiling, weather'. Heat transfer mode frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1045

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Significant figures in 0.004050:

A. 7

B. 3

C. 5

D. 4

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Correct Answer: Option D

Explanation:
Rules: leading zeros not significant; trailing zero after decimal is significant. Digits 4,0,5,0 are significant ⇒ 4 sig figs. Memory tip: 'Start at first non-zero; include trailing zeros after decimal'. Measurement precision concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1046

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Three forces in equilibrium: if two are equal and at 120°, third force is:

A. Zero

B. Sum of two

C. Equal to each, at 120° to both

D. Difference of two

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Correct Answer: Option C

Explanation:
Vector equilibrium: three equal forces at 120° form closed triangle. Third force equals magnitude of others, oriented 120° from each. Memory aid: 'Equilibrium: vector sum = 0; symmetric forces ⇒ symmetric angles'. Statics concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1047

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Medium n=2. Light speed in medium:

A. 1.5×10⁸ m/s

B. 0.5×10⁸ m/s

C. 6×10⁸ m/s

D. 3×10⁸ m/s

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Correct Answer: Option A

Explanation:
v = c/n = 3×10⁸/2 = 1.5×10⁸ m/s. Direct refractive index application. Memory tip: 'Higher n ⇒ slower light; v = c/n'. Optics calculation frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1048

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KE increased by 100%. Momentum increase percentage:

A. 100%

B. 41.4%

C. 50%

D. 200%

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Correct Answer: Option B

Explanation:
KE ∝ p². Double KE ⇒ p_new = √2 p_old ⇒ increase = (√2 - 1)×100% ≈ 41.4%. Memory tip: 'KE ∝ p²; %Δp ≈ ½ %ΔKE for small changes, but use exact for large'. Energy-momentum relation frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1049

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Radioactive decay to 1/32 initial: number of half-lives:

A. 3

B. 4

C. 6

D. 5

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Correct Answer: Option D

Explanation:
(1/2)ⁿ = 1/32 ⇒ 2ⁿ = 32 ⇒ n = 5 half-lives. Exponential decay calculation. Memory aid: '1/2ⁿ remaining; 1/32 = 1/2⁵ ⇒ 5 half-lives'. Radioactivity arithmetic frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1050

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Potentiometer sensitivity increased by:

A. Thicker wire

B. Shorter wire

C. Longer wire

D. Higher current

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Correct Answer: Option C

Explanation:
Longer wire ⇒ smaller potential gradient (V/cm) ⇒ finer voltage measurement ⇒ higher sensitivity. Memory tip: 'Sensitivity ∝ wire length; smaller gradient = better resolution'. Experimental physics concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1051

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Superconductivity characterized by:

A. Infinite resistance

B. High conductivity only

C. Zero resistance below T_c

D. Zero permeability

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Correct Answer: Option C

Explanation:
Superconductors: zero electrical resistance below critical temperature T_c, plus Meissner effect (expel magnetic fields). Memory aid: 'Superconductor: R=0 below T_c; perfect diamagnetism'. Modern physics concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1052

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Torque dimensions same as:

A. Work

B. Power

C. Momentum

D. Force

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Correct Answer: Option A

Explanation:
Torque τ = r×F: [L][MLT⁻²] = [ML²T⁻²]. Work W = F·d: same dimensions. Physically distinct: torque (vector, rotational), work (scalar, energy). Memory tip: 'Torque and work: same [ML²T⁻²]; different physical meaning'. Dimensional analysis frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1053

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Convex lens in water: focal length:

A. Decreases

B. Increases

C. Becomes negative

D. Unchanged

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Correct Answer: Option B

Explanation:
Lens maker: 1/f ∝ (n_rel - 1). In water, n_rel = n_glass/n_water ≈ 1.5/1.33 ≈ 1.13 < 1.5 (air). Smaller (n_rel-1) ⇒ larger f. Memory aid: 'Lens in denser medium: reduced power ⇒ longer focal length'. Optics application frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1054

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Escape velocity depends on:

A. Planet mass and radius

B. Projectile mass

C. Atmosphere

D. Launch angle

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Correct Answer: Option A

Explanation:
v_e = √(2GM/R): depends on planet's M and R, independent of projectile mass or launch direction. Memory tip: 'v_e ∝ √(M/R); property of planet, not projectile'. Gravitation concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1055

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Interference demonstrates light's:

A. Neither

B. Wave nature

C. Particle nature

D. Both

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Correct Answer: Option B

Explanation:
Interference (constructive/destructive superposition) is wave phenomenon. Young's double-slit confirmed light's wave nature. Particle nature shown by photoelectric effect. Memory aid: 'Interference/diffraction ⇒ wave; photoelectric ⇒ particle'. Wave-particle duality frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1056

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AC RMS value defined for equivalent:

A. Charge flow

B. Magnetic field

C. Voltage

D. Heating effect

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Correct Answer: Option D

Explanation:
I_rms defined so I_rms²R = average power, same heating as DC current. For sine wave: I_rms = I₀/√2. Memory tip: 'RMS: heating equivalence; use RMS for power calculations'. AC fundamentals frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1057

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Low Earth orbit satellite period:

A. 84 minutes

B. 90 minutes

C. 12 hours

D. 24 hours

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Correct Answer: Option A

Explanation:
T = 2π√(R/g) ≈ 5076 s ≈ 84.6 min for r ≈ Earth radius. Standard result. Memory aid: 'Low orbit: ~84 min; geostationary: 24 hours'. Orbital mechanics fact frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1058

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Water's high specific heat useful for:

A. Engine cooling

B. Biological temperature regulation

C. Both

D. Neither

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Correct Answer: Option C

Explanation:
High c = absorbs/releases large heat with small ΔT. Stabilizes engine temperatures and organism body temperatures. Memory tip: 'High specific heat = thermal buffer; water moderates climate and physiology'. Property application frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1059

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Photoelectric emission requires:

A. Frequency > threshold

B. Any frequency with high intensity

C. Long wavelength

D. High intensity

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Correct Answer: Option A

Explanation:
Emission requires photon energy hν ≥ work function φ ⇒ ν ≥ ν₀. Intensity affects electron count, not emission possibility. Memory aid: 'Photoelectric: frequency threshold (quantum); intensity affects current'. Quantum physics concept frequently tested in competitive exams.

This question belongs to: Science Physics

Question #1060

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Wavelength measurement instrument:

A. Spectrometer

B. Telescope

C. Microscope

D. Galvanometer

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Correct Answer: Option A

Explanation:
Spectrometer uses diffraction grating/prism to disperse light and measure wavelengths via angular positions. Memory tip: 'Spectrometer = wavelength via dispersion; used in spectroscopy'. Instrument application frequently tested in competitive exams.

This question belongs to: Science Physics

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