Physics Questions

Found 13 practice questions from various admission tests.

1. The SI unit of force is:

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A. Joule

B. Watt

C. Newton✓ Correct

D. Pascal

Explanation: Force = mass × acceleration. The SI unit is Newton (N) = kg⋅m/s².

2. A body at rest has:

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A. Speed

B. Velocity

C. Momentum

D. Inertia✓ Correct

Explanation: Inertia is the tendency of a body to resist changes in its state of motion or rest.

3. The speed of light in vacuum is approximately:

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A. 3 × 10⁶ m/s

B. 3 × 10⁸ m/s✓ Correct

C. 3 × 10¹⁰ m/s

D. 3 × 10⁵ m/s

Explanation: The speed of light in vacuum is approximately 3 × 10⁸ m/s (299,792,458 m/s).

4. Which mirror is used by dentists to examine teeth?

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A. Plane mirror

B. Convex mirror

C. Concave mirror✓ Correct

D. None

Explanation: Concave mirrors produce magnified virtual images when object is between pole and focus.

5. The unit of electrical resistance is:

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A. Volt

B. Ampere

C. Ohm✓ Correct

D. Watt

Explanation: Resistance is measured in Ohms (Ω). R = V/I (Ohm's law).

6. What is the acceleration due to gravity on Earth's surface?

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A. 8.9 m/s²

B. 9.8 m/s²✓ Correct

C. 10.8 m/s²

D. 11.2 m/s²

Explanation: The standard value of g on Earth's surface is approximately 9.8 m/s².

7. Sound waves are:

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A. Transverse waves

B. Longitudinal waves✓ Correct

C. Electromagnetic waves

D. Standing waves

Explanation: Sound travels through compressions and rarefactions, making it a longitudinal wave.

8. Which color of light has the longest wavelength?

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A. Violet

B. Blue

C. Green

D. Red✓ Correct

Explanation: Red light has the longest wavelength (~700nm) in the visible spectrum.

9. A Carnot engine operates between 400K and 300K. What is its maximum efficiency?

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A. 25%✓ Correct

B. 33.3%

C. 50%

D. 75%

Explanation: Efficiency η = 1 - (Tc/Th) = 1 - (300/400) = 1 - 0.75 = 0.25 = 25%.

10. If the kinetic energy of a particle is doubled, its momentum increases by a factor of:

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A. 2

B. 4

C. √2✓ Correct

D. 1/√2

Explanation: KE = p²/2m. So p = √(2m*KE). If KE is doubled, p becomes √(2m*2*KE) = √2 * p.

11. Two resistors of 4Ω and 6Ω are connected in parallel. What is their equivalent resistance?

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A. 10Ω

B. 2.4Ω✓ Correct

C. 24Ω

D. 1.5Ω

Explanation: 1/R_eq = 1/4 + 1/6 = 3/12 + 2/12 = 5/12. R_eq = 12/5 = 2.4Ω.

12. What is the dimensional formula of torque?

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A. MLT⁻²

B. ML²T⁻²✓ Correct

C. ML²T⁻¹

D. M²LT⁻²

Explanation: Torque = Force × distance. Force = MLT⁻², distance = L. So Torque = ML²T⁻².

13. The escape velocity from Earth is approximately:

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A. 9.8 km/s

B. 11.2 km/s✓ Correct

C. 15.0 km/s

D. 3.0 km/s

Explanation: Escape velocity = √(2gR) ≈ 11.2 km/s.