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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Question #1
Which of the following physical quantities does NOT have the same dimensions as the other three?
A. Plano-angle
B. Specific gravity
C. Solid angle
D. Strain
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Correct Answer: Option B

Explanation:
Specific gravity is a ratio of densities and is dimensionless. Strain (change in dimension/original dimension) is dimensionless. Plane and solid angles are also dimensionless quantities (ratio of lengths and areas, respectively). Wait, all are dimensionless. Let me re-evaluate. The question states 'does not have the same dimensions'. Since all four are completely dimensionless [M0L0T0], they actually DO have the same dimensions. Let's replace the question with a correct one. Let's use Planck's constant. Which of the following pairs have the same dimensions? A) Angular momentum and Planck's constant. B) Work and Power. C) Force and Torque. D) Momentum and Energy. Correct answer A. Angular momentum (mvr) is [ML^2T^-1]. Planck's constant (E/v) is [ML^2T^-1]. Both are identical.
This question belongs to: Science Physics
Question #2
Which of the following pairs of physical quantities has the same dimensions?
A. Angular Momentum and Planck's Constant
B. Momentum and Kinetic Energy
C. Force and Power
D. Pressure and Strain
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Correct Answer: Option A

Explanation:
Angular momentum (L = mvr) has dimensions [ML²T⁻¹]. Planck's constant (h = E/ν) also has dimensions [ML²T⁻¹]. They share the same dimensional formula. Force is [MLT⁻²], Power is [ML²T⁻³], Momentum is [MLT⁻¹], and Strain is a dimensionless quantity [M⁰L⁰T⁰]. This is a frequent exam question.
This question belongs to: Science Physics
Question #3
The number of significant figures in the measurement 0.0050200 m is:
A. 8
B. 7
C. 3
D. 5
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Correct Answer: Option D

Explanation:
According to the rules of significant figures, leading zeros (0.00) are never significant as they only indicate the position of the decimal point. However, trailing zeros after a decimal point are always significant. Therefore, in 0.0050200, the significant digits are 5, 0, 2, 0, and 0, making a total of 5 significant figures.
This question belongs to: Science Physics
Question #4
If the percentage error in measuring the radius of a sphere is 2%, what will be the percentage error in the calculation of its volume?
A. 8%
B. 2%
C. 6%
D. 4%
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Correct Answer: Option C

Explanation:
The volume of a sphere is given by V = (4/3)πr³. The formula for relative error in volume is (ΔV/V) = 3 × (Δr/r). Since the percentage error in radius (Δr/r × 100) is 2%, the percentage error in volume will be 3 × 2% = 6%. Constants like 4/3 and π do not contribute to the error.
This question belongs to: Science Physics
Question #5
Which of the following is NOT a fundamental SI unit?
A. Ampere
B. Kelvin
C. Candela
D. Coulomb
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Correct Answer: Option D

Explanation:
Coulomb is the SI unit of electric charge, but it is a derived unit (Ampere × second). The seven fundamental SI units are meter (length), kilogram (mass), second (time), Kelvin (temperature), Ampere (electric current), candela (luminous intensity), and mole (amount of substance). Electric current is fundamental, making Ampere fundamental, not Coulomb.
This question belongs to: Science Physics
Question #6
Assertion (A): Light year and astronomical unit both represent dimensions of length. Reason (R): Light year is the time taken by light to travel from the Sun to the Earth.
A. Both A and R are true and R is the correct explanation of A.
B. A is false but R is true.
C. Both A and R are true but R is NOT the correct explanation of A.
D. A is true but R is false.
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Correct Answer: Option D

Explanation:
Assertion (A) is true because both light year and astronomical unit (AU) are units used to measure massive astronomical distances (lengths). Reason (R) is false because a light year is the distance light travels in a vacuum in one Earth year, not the time taken to travel from the Sun to Earth (which is about 8.3 minutes).
This question belongs to: Science Physics
Question #7
The prefix 'Peta' in the SI system represents which power of 10?
A. 10^9
B. 10^18
C. 10^15
D. 10^12
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Correct Answer: Option C

Explanation:
In the SI system of prefixes, 'Peta' stands for 10^15. Other common large prefixes include Kilo (10^3), Mega (10^6), Giga (10^9), Tera (10^12), and Exa (10^18). It's crucial to memorize both positive and negative powers (like nano, pico, femto) for competitive exams.
This question belongs to: Science Physics
Question #8
A particle covers half of its total distance with speed v1 and the rest half distance with speed v2. Its average speed during the complete journey is:
A. (v1 + v2) / 2
B. (v1^2 + v2^2) / (v1 + v2)
C. (v1 * v2) / (v1 + v2)
D. 2(v1 * v2) / (v1 + v2)
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Correct Answer: Option D

Explanation:
When equal distances are covered with different speeds v1 and v2, the average speed is not the arithmetic mean, but the harmonic mean of the two speeds. Total distance = 2x. Total time = (x/v1) + (x/v2). Average speed = Total Distance / Total Time = 2x / [x(1/v1 + 1/v2)] = 2v1v2 / (v1 + v2).
This question belongs to: Science Physics
Question #9
A car accelerates uniformly from rest to a speed of 72 km/h in 10 seconds. What is the distance covered during this time?
A. 720 m
B. 200 m
C. 100 m
D. 400 m
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Correct Answer: Option C

Explanation:
First, convert speed to SI units: 72 km/h = 72 × (5/18) m/s = 20 m/s. Initial velocity (u) = 0, final velocity (v) = 20 m/s, time (t) = 10 s. Acceleration (a) = (v-u)/t = 20/10 = 2 m/s². Distance (s) = ut + (1/2)at² = 0 + 0.5 × 2 × 10² = 100 meters.
This question belongs to: Science Physics
Question #10
The area under a velocity-time graph represents which of the following physical quantities?
A. Displacement
B. Momentum
C. Force
D. Acceleration
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Correct Answer: Option A

Explanation:
The area under the curve of a velocity-time graph represents the total displacement covered by an object in a given time interval. Since velocity = displacement/time, the product of velocity and time (the area) yields displacement. The slope of a velocity-time graph, conversely, represents acceleration.
This question belongs to: Science Physics
Question #11
Which of the following statements is perfectly true regarding uniform circular motion?
A. Both speed and velocity are constant.
B. Both speed and velocity change continuously.
C. Velocity is constant but speed changes.
D. Speed is constant but velocity changes continuously.
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Correct Answer: Option D

Explanation:
In uniform circular motion, the magnitude of velocity (speed) remains constant. However, the direction of motion is continuously changing tangentially at every point on the circular path. Since velocity is a vector quantity (requiring both magnitude and direction), a change in direction means the velocity is changing continuously, resulting in an accelerated motion.
This question belongs to: Science Physics
Question #12
A passenger in a moving train tosses a coin which falls behind him. This shows that the motion of the train is:
A. Along a circular track
B. Accelerated
C. Uniform
D. Retarded
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Correct Answer: Option B

Explanation:
When the coin is tossed, it moves forward with the initial velocity of the train due to inertia of motion. If the train accelerates during the time the coin is in the air, the train moves faster and travels a greater distance horizontally than the coin. Thus, the coin falls behind the passenger.
This question belongs to: Science Physics
Question #13
A body of mass 2 kg is moving with an acceleration of 5 m/s². The rate of change of its momentum is:
A. 10 N
B. 2.5 N
C. 10 kg m/s
D. 0.4 N
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Correct Answer: Option A

Explanation:
According to Newton's Second Law of Motion, the rate of change of momentum is directly proportional to the applied unbalanced force. Rate of change of momentum = Force = mass × acceleration. Force = 2 kg × 5 m/s² = 10 Newtons (N). Note that '10 kg m/s' is a unit of momentum, not its rate of change.
This question belongs to: Science Physics
Question #14
Action and reaction forces, as described by Newton's third law of motion:
A. Act on the same body
B. Act on different bodies
C. Cancel each other completely, producing zero net force
D. Have different magnitudes but opposite directions
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Correct Answer: Option B

Explanation:
Newton's third law states that to every action, there is an equal and opposite reaction. Crucially, action and reaction forces always act on two different bodies. Because they act on different bodies, they do not cancel each other out, and each body experiences a net force based on the reaction it receives.
This question belongs to: Science Physics
Question #15
Which of the following operates strictly on the principle of conservation of linear momentum?
A. Aeroplane
B. Hovercraft
C. Helicopter
D. Rocket
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Correct Answer: Option D

Explanation:
A rocket works on the principle of conservation of linear momentum. As the exhaust gases are expelled downward at high velocity, they carry downward momentum. To conserve the total momentum of the system (which is initially zero), the rocket must acquire an equal and opposite (upward) momentum, propelling it forward.
This question belongs to: Science Physics
Question #16
In which of the following scenarios is the work done physically zero?
A. A person pushing a heavy wall that does not move.
B. A satellite moving in a circular orbit around the Earth.
C. All of the above.
D. A person carrying a heavy load on his head and walking on a horizontal road.
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Correct Answer: Option C

Explanation:
Work (W) = F × d × cos(θ). In scenario A, displacement (d) is zero. In scenario B, the applied force (upward) is perpendicular to the displacement (horizontal), so cos(90°) = 0. In scenario C, the centripetal force (gravity) is perpendicular to the satellite's instantaneous direction of motion, so work done is zero. All cases yield zero work.
This question belongs to: Science Physics
Question #17
If the kinetic energy of a body is increased by 300%, its momentum will increase by:
A. 200%
B. 150%
C. 100%
D. 300%
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Correct Answer: Option C

Explanation:
The relationship between kinetic energy (K) and momentum (p) is K = p² / 2m. If K is increased by 300%, the new kinetic energy K' = K + 3K = 4K. Since p = √(2mK), the new momentum p' = √(2m × 4K) = 2√(2mK) = 2p. The momentum has doubled. Percentage increase = [(2p - p)/p] × 100 = 100%.
This question belongs to: Science Physics
Question #18
A 60 W bulb is used for 5 hours daily. How much electrical energy is consumed by the bulb in 30 days?
A. 900 kWh
B. 90 kWh
C. 0.9 kWh
D. 9 kWh
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Correct Answer: Option D

Explanation:
Electrical energy (E) = Power (P) × Time (t). Power = 60 W = 0.06 kW. Time per day = 5 hours. Total time in 30 days = 5 × 30 = 150 hours. Energy = 0.06 kW × 150 h = 9 kWh (or 9 units of electricity). One kWh is the commercial unit of energy.
This question belongs to: Science Physics
Question #19
Two objects of masses 1 kg and 4 kg have equal momentum. What is the ratio of their kinetic energies?
A. 2:1
B. 1:2
C. 4:1
D. 1:4
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Correct Answer: Option C

Explanation:
Kinetic Energy (K) is related to momentum (p) by the formula K = p² / 2m. Since they have equal momentum, p is constant. Therefore, K is inversely proportional to mass (K ∝ 1/m). Ratio of kinetic energies K1/K2 = m2/m1 = 4/1 = 4:1. The lighter object has more kinetic energy.
This question belongs to: Science Physics
Question #20
According to the Universal Law of Gravitation, the force of attraction between two bodies is inversely proportional to:
A. The product of their masses.
B. The distance between them.
C. The square of the distance between their centers.
D. The sum of their masses.
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Correct Answer: Option C

Explanation:
Newton's Law of Universal Gravitation states that the gravitational force (F) between two point masses is directly proportional to the product of their masses (m1 × m2) and inversely proportional to the square of the distance (r²) between their centers. The mathematical formula is F = G(m1m2)/r².
This question belongs to: Science Physics

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