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 19 of 65
Question #361
The energy equivalent of 1 amu is approximately
A. 931 MeV
B. 3.0 × 10⁸ J
C. 1.6 × 10⁻¹⁹ J
D. 931 eV
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Correct Answer: Option A

Explanation:
1 amu = 1.6605 × 10⁻²⁷ kg, using E=mc² gives about 931.5 MeV. Used in nuclear binding energy calculations. Not eV, but MeV. Very large energy per nucleon.
This question belongs to: Science Physics
Question #362
The mirror used as rear-view mirror in vehicles is
A. Parabolic mirror
B. Plane mirror
C. Convex mirror
D. Concave mirror
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Correct Answer: Option C

Explanation:
Convex mirror gives wider field of view, always forms virtual, erect, diminished image. Allows driver to see larger area. Concave can magnify but field narrow. Plane gives normal view but limited field.
This question belongs to: Science Physics
Question #363
The wavelength of ultrasonic waves is
A. Greater than audible sound
B. Cannot be determined
C. Less than audible sound
D. Same as audible sound
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Correct Answer: Option C

Explanation:
Velocity v = fλ constant for given medium. Ultrasound has higher frequency (>20 kHz) than audible sound, so wavelength λ = v/f is smaller. Typical ultrasound in MHz range, λ in mm.
This question belongs to: Science Physics
Question #364
A pressure cooker reduces cooking time because
A. More water is used
B. High pressure increases boiling point
C. Low pressure decreases boiling point
D. It absorbs more heat
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Correct Answer: Option B

Explanation:
Higher pressure raises boiling point, so water can reach temperatures above 100°C, cooking food faster. At high altitudes, pressure cooker compensates for lower atmospheric pressure.
This question belongs to: Science Physics
Question #365
The chemical name of 'solar cell' material commonly used is
A. Copper oxide
B. Selenium
C. Silicon
D. Germanium
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Correct Answer: Option C

Explanation:
Most solar cells use silicon (monocrystalline or polycrystalline). Other materials: gallium arsenide, cadmium telluride. Silicon is semiconductor, abundant, efficient. Converts sunlight to electricity.
This question belongs to: Science Physics
Question #366
The device used for detecting and measuring small electric current is
A. Wattmeter
B. Ammeter
C. Galvanometer
D. Voltmeter
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Correct Answer: Option C

Explanation:
Galvanometer is sensitive instrument for detecting presence and direction of small currents. Ammeter measures larger currents. Voltmeter potential difference. Wattmeter power.
This question belongs to: Science Physics
Question #367
Which of the following is an example of the Doppler effect?
A. Fusion of nuclei
B. Echo of sound
C. Bending of light around corners
D. Change in frequency of siren as ambulance passes
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Correct Answer: Option D

Explanation:
Doppler effect: apparent change in frequency due to relative motion. Siren pitch changes as it approaches/recedes. Echo is reflection. Bending is diffraction. Fusion is nuclear reaction.
This question belongs to: Science Physics
Question #368
The unit of magnetic field strength is
A. Tesla
B. Farad
C. Henry
D. Weber
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Correct Answer: Option A

Explanation:
Tesla (T) = N/(A·m) = Wb/m². Weber is magnetic flux. Henry is inductance. Farad is capacitance. Gauss is another unit (1 T = 10⁴ G).
This question belongs to: Science Physics
Question #369
The time period of a satellite in low Earth orbit is about
A. 365 days
B. 12 hours
C. 24 hours
D. 90 minutes
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Correct Answer: Option D

Explanation:
Low Earth orbit (LEO) satellites (altitude ~200-2000 km) have orbital period ~90 minutes. ISS orbits in ~93 min. Geostationary orbit period 24 h. Moon 27 days. Kepler's third law applies.
This question belongs to: Science Physics
Question #370
The instrument that measures atmospheric pressure is
A. Manometer
B. Lactometer
C. Barometer
D. Hydrometer
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Correct Answer: Option C

Explanation:
Barometer measures atmospheric pressure. Mercury barometer (Torricelli) standard. Aneroid barometer. Manometer measures pressure difference. Hydrometer density. Lactometer milk purity.
This question belongs to: Science Physics
Question #371
Which of the following colours has the longest wavelength?
A. Red
B. Blue
C. Green
D. Violet
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Correct Answer: Option A

Explanation:
Visible spectrum: red ~700 nm, orange, yellow, green, blue, indigo, violet ~400 nm. Red has longest wavelength, lowest frequency. Violet shortest wavelength, highest frequency. Remember VIBGYOR.
This question belongs to: Science Physics
Question #372
The value of universal gravitational constant G is
A. Both A and C
B. 6.67 × 10⁻¹¹ dyne cm²/g²
C. 6.67 × 10⁻¹¹ N m²/kg²
D. 9.8 m/s²
Discuss
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Correct Answer: Option A

Explanation:
G = 6.67 × 10⁻¹¹ N m²/kg² in SI, and 6.67 × 10⁻⁸ dyne cm²/g² in CGS. Both are correct. Important constant, measured by Cavendish. g is acceleration due to gravity, different.
This question belongs to: Science Physics
Question #373
A fuse wire should have
A. Low melting point and low resistance
B. High melting point and low resistance
C. High melting point and high resistance
D. Low melting point and high resistance
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Correct Answer: Option D

Explanation:
Fuse wire must melt easily (low melting point) to break circuit on overload, and have high resistance to produce sufficient heat (I²R). Materials: tin-lead alloy. Copper not used as fuse.
This question belongs to: Science Physics
Question #374
The scientist who invented the electric generator is
A. Thomas Edison
B. Nikola Tesla
C. Michael Faraday
D. James Watt
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Correct Answer: Option C

Explanation:
Michael Faraday built the first electric generator (Faraday disk) in 1831, based on electromagnetic induction. Tesla contributed to AC motor and polyphase system. Edison DC systems. Watt steam engine.
This question belongs to: Science Physics
Question #375
When a body is taken from equator to pole, its weight
A. Increases
B. Becomes zero
C. Decreases
D. Remains same
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Correct Answer: Option A

Explanation:
g is slightly higher at poles (9.83 m/s²) than equator (9.78 m/s²) due to Earth's rotation (centrifugal effect) and equatorial bulge. Weight = mg, so weight increases slightly. Mass constant.
This question belongs to: Science Physics
Question #376
A wire of resistance R is cut into three equal parts. These parts are then connected in parallel. The equivalent resistance is
A. R
B. 3R
C. R/9
D. R/3
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Correct Answer: Option C

Explanation:
Each part resistance = R/3. Three such in parallel: 1/R_eq = 3/(R/3) = 9/R => R_eq = R/9. For n equal parts cut and connected parallel, R_eq = R/n².
This question belongs to: Science Physics
Question #377
The image formed by a plane mirror is
A. Real and erect
B. Real and inverted
C. Virtual and erect
D. Virtual and inverted
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Correct Answer: Option C

Explanation:
Plane mirror forms virtual, erect, same size, laterally inverted image behind mirror. Used in periscope, looking glass. Distance behind mirror equals object distance.
This question belongs to: Science Physics
Question #378
The substance that sublimes is
A. Water
B. Iron
C. Ice
D. Naphthalene
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Correct Answer: Option D

Explanation:
Naphthalene (mothballs), camphor, dry ice sublime (solid → gas). Ice melts. Iron solid till melting. Water evaporates from liquid. Sublimation skips liquid phase.
This question belongs to: Science Physics
Question #379
The principle of a microwave oven is
A. Induction heating
B. Infrared radiation
C. Dielectric heating
D. Convection heating
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Correct Answer: Option C

Explanation:
Microwaves (2.45 GHz) are absorbed by water, fat, sugar molecules, causing them to rotate and generate heat through dielectric heating. Not induction (metal). Not conventional convection.
This question belongs to: Science Physics
Question #380
The diameter of an atom is approximately
A. 10⁻¹⁰ m
B. 10⁻³ m
C. 10⁻⁶ m
D. 10⁻¹⁵ m
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Correct Answer: Option A

Explanation:
Atomic diameter ~ 1 Å = 10⁻¹⁰ m. Nucleus is 10⁻¹⁵ m (femtometre). Atomic size determined by electron cloud. 10⁻⁶ m is typical cell size. 10⁻³ m is millimetre.
This question belongs to: Science Physics

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