Physics MCQs

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Physics MCQs

Practice the latest Physics MCQs with answers and detailed explanations. This section includes chapter-wise multiple-choice questions covering mechanics, motion, force, work and energy, heat, light, electricity, magnetism, modern physics, waves, optics, and other important topics. These exam-oriented MCQs are ideal for Class 9–12, NEET, JEE, CUET, SSC, Banking, Railway, JKSSB, Defence, Police, and other competitive exams.

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Page 13 of 65
Question #241
The gravitational force between two masses is F. If the distance between them is halved, the force becomes
A. 4F
B. 2F
C. F/2
D. F/4
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Correct Answer: Option A

Explanation:
Newton's law of gravitation: F ∝ 1/r². If distance r becomes r/2, new force F' ∝ 1/(r/2)² = 4/r² = 4F. So force quadruples. This inverse square law is fundamental for gravitational, electric, magnetic forces.
This question belongs to: Science Physics
Question #242
The value of acceleration due to gravity g on the surface of Earth depends on
A. Rotation of the object
B. Mass of the object
C. Mass of the Earth
D. Shape of the object
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Correct Answer: Option C

Explanation:
g = GM/R², where M is mass of Earth, R radius, G universal constant. It does not depend on mass of falling object (Galileo's experiment). Earth's rotation causes slight variation but surface g is primarily determined by M and R. So mass of Earth is factor.
This question belongs to: Science Physics
Question #243
Weight of an object on the Moon is about _____ of its weight on Earth.
A. 1/4
B. 1/6
C. 1/2
D. 1/8
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Correct Answer: Option B

Explanation:
Moon's gravity is about 1/6th of Earth's gravity. So weight (mg) is 1/6 of Earth weight. Mass remains same. g_moon ≈ 1.62 m/s², g_earth ≈ 9.8 m/s², ratio ≈ 1/6. Common fact in space science.
This question belongs to: Science Physics
Question #244
Which of the following is true for a geostationary satellite?
A. It revolves opposite to Earth's rotation
B. It appears fixed relative to a point on Earth
C. Its orbit is at any altitude
D. Its orbital period is 12 hours
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Correct Answer: Option B

Explanation:
Geostationary satellite has orbital period equal to Earth's rotation (24 hours) and orbits in equatorial plane in same direction. It appears stationary from Earth's surface. Altitude about 36,000 km. Used for communication.
This question belongs to: Science Physics
Question #245
Atmospheric pressure at sea level in pascal is approximately
A. 1.01 × 10⁹ Pa
B. 1.01 × 10⁵ Pa
C. 1.01 × 10³ Pa
D. 1.01 × 10⁷ Pa
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Correct Answer: Option B

Explanation:
Standard atmospheric pressure 1 atm = 1.01325 × 10⁵ Pa ≈ 1.01 × 10⁵ Pa = 101 kPa. Also equals 760 mm of Hg. This is an important conversion for pressure units.
This question belongs to: Science Physics
Question #246
According to Pascal's law, pressure applied to an enclosed fluid is transmitted
A. With loss of magnitude
B. Only in downward direction
C. In direction of flow only
D. Undiminished in all directions
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Correct Answer: Option D

Explanation:
Pascal's law: pressure applied to a confined incompressible fluid is transmitted equally and undiminished in all directions. Hydraulic lift, hydraulic brakes work on this principle. P = F₁/A₁ = F₂/A₂.
This question belongs to: Science Physics
Question #247
A body fully immersed in a fluid experiences an upward buoyant force equal to
A. Density of the body
B. Volume of the body
C. Weight of the fluid displaced
D. Weight of the body
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Correct Answer: Option C

Explanation:
Archimedes' principle: buoyant force = weight of fluid displaced. This force acts upward. If buoyant force ≥ weight, object floats. Submarines use ballast tanks to change weight, altering buoyancy.
This question belongs to: Science Physics
Question #248
A hydrometer is used to measure
A. Density of liquids
B. Atmospheric pressure
C. Wind speed
D. Humidity
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Correct Answer: Option A

Explanation:
Hydrometer measures relative density (specific gravity) of liquids based on floatation principle. Deeper sinking indicates less dense liquid. Hygrometer measures humidity, anemometer wind speed, barometer pressure.
This question belongs to: Science Physics
Question #249
A cork floats on water because its density is
A. Zero
B. Equal to that of water
C. Less than that of water
D. Greater than that of water
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Correct Answer: Option C

Explanation:
Objects float if their density is less than the fluid. Cork density < water density, so it floats. Iron sinks because density > water. Ship made of iron floats due to shape displacing more water, average density less.
This question belongs to: Science Physics
Question #250
The boiling point of water at high altitude is lower because
A. Temperature is lower
B. Gravity is less
C. Atmospheric pressure is higher
D. Atmospheric pressure is lower
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Correct Answer: Option D

Explanation:
Boiling occurs when vapour pressure equals atmospheric pressure. At high altitude, atmospheric pressure is lower, so water boils at lower temperature. Pressure cooker increases pressure to raise boiling point for faster cooking.
This question belongs to: Science Physics
Question #251
Heat transfer in vacuum occurs by
A. Radiation
B. Convection
C. Both conduction and convection
D. Conduction
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Correct Answer: Option A

Explanation:
Radiation does not require medium; it travels via electromagnetic waves. Conduction needs medium for molecular collisions, convection needs fluid motion. Sun's heat reaches Earth by radiation through vacuum of space.
This question belongs to: Science Physics
Question #252
Specific heat capacity of water is 4200 J/kg°C. How much heat is required to raise temperature of 2 kg water by 10°C?
A. 4200 J
B. 8400 J
C. 84000 J
D. 42000 J
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Correct Answer: Option C

Explanation:
Q = mcΔθ = 2 × 4200 × 10 = 84,000 J = 84 kJ. Large specific heat of water makes it useful for cooling and climate moderation. Always check units: mass kg, c J/kg°C, ΔT °C.
This question belongs to: Science Physics
Question #253
The process of change from solid directly to vapour is called
A. Freezing
B. Condensation
C. Melting
D. Sublimation
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Correct Answer: Option D

Explanation:
Sublimation: solid → gas without liquid phase. Example: camphor, naphthalene balls, dry ice (solid CO₂). Deposition is reverse. Latent heat of sublimation involved.
This question belongs to: Science Physics
Question #254
A bimetallic strip bends on heating due to
A. Different melting points
B. Different specific heats
C. Different densities
D. Different thermal expansion coefficients
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Correct Answer: Option D

Explanation:
Bimetallic strip consists of two metals with different coefficients of linear expansion. On heating, one expands more, causing bending. Used in thermostats, fire alarms. Expansion difference causes curvature.
This question belongs to: Science Physics
Question #255
The SI unit of temperature is
A. Kelvin
B. Celsius
C. Fahrenheit
D. Reaumur
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Correct Answer: Option A

Explanation:
SI base unit of thermodynamic temperature is kelvin (K). Celsius is derived unit, size 1°C = 1 K. Fahrenheit and Reaumur are other scales. Kelvin scale starts at absolute zero.
This question belongs to: Science Physics
Question #256
The frequency of a sound wave is 200 Hz. Its time period is
A. 200 s
B. 0.005 s
C. 0.02 s
D. 0.05 s
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Correct Answer: Option B

Explanation:
Time period T = 1/f = 1/200 = 0.005 s = 5 ms. Frequency is number of cycles per second. Relationship T = 1/f is fundamental. For 200 Hz, period is 5 milliseconds.
This question belongs to: Science Physics
Question #257
The pitch of a sound depends on its
A. Frequency
B. Wavelength
C. Speed
D. Amplitude
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Correct Answer: Option A

Explanation:
Pitch is subjective perception of frequency. Higher frequency higher pitch. Amplitude determines loudness. Speed and wavelength related by v = fλ, but pitch is frequency-based. Human ear 20 Hz-20 kHz.
This question belongs to: Science Physics
Question #258
An echo is heard after 2 seconds from a cliff. If speed of sound is 340 m/s, distance of cliff is
A. 680 m
B. 340 m
C. 170 m
D. 510 m
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Correct Answer: Option B

Explanation:
Sound travels to cliff and back. Total distance = speed × time = 340 × 2 = 680 m. So distance to cliff = 680/2 = 340 m. Use formula d = (v × t)/2. Time for round trip. Minimum distance for echo 17 m (approx) for 0.1 s persistence.
This question belongs to: Science Physics
Question #259
Which of the following waves is longitudinal?
A. Radio waves
B. Waves on a string
C. Sound waves in air
D. Light waves
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Correct Answer: Option C

Explanation:
Sound waves in air are longitudinal, particles vibrate parallel to wave propagation. Light and radio are electromagnetic, transverse. Waves on a string are transverse. In fluids, only longitudinal mechanical waves can propagate.
This question belongs to: Science Physics
Question #260
The phenomenon of apparent change in frequency due to relative motion between source and observer is called
A. Echo
B. Doppler effect
C. Diffraction
D. Resonance
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Correct Answer: Option B

Explanation:
Doppler effect: observed frequency higher when approaching, lower when receding. Applications: radar speed guns, astronomical redshift/blueshift, echocardiography. Echo is reflection. Resonance is vibration matching. Diffraction is bending.
This question belongs to: Science Physics

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