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Q.1 Medium Physics

A body moves in a circle of radius 5 m with constant speed 10 m/s. What is the centripetal acceleration?

A 2 m/s²

B 20 m/s²

C 50 m/s²

D 100 m/s²

Correct Answer: B. 20 m/s²

Explanation:

Centripetal acceleration a = v²/r = (10)²/5 = 100/5 = 20 m/s².

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Q.2 Medium Physics

Two capacitors of 2 μF and 3 μF are connected in series. What is the equivalent capacitance?

A 5 μF

B 1.2 μF

C 6 μF

D 0.5 μF

Correct Answer: B. 1.2 μF

Explanation:

For capacitors in series: 1/C = 1/C₁ + 1/C₂ = 1/2 + 1/3 = 5/6. Therefore C = 6/5 = 1.2 μF.

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Q.3 Medium Physics

A ball is thrown vertically upward with initial velocity 20 m/s. What maximum height does it reach? (g = 10 m/s²)

A 10 m

B 20 m

C 30 m

D 40 m

Correct Answer: B. 20 m

Explanation:

At maximum height, v = 0. Using v² = u² - 2gh: 0 = 20² - 2(10)h. 20h = 400. h = 20 m.

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Q.4 Medium Physics

Which law of thermodynamics explains why heat cannot spontaneously flow from a colder body to a hotter body?

A First Law of Thermodynamics

B Second Law of Thermodynamics

C Third Law of Thermodynamics

D Zeroth Law of Thermodynamics

Correct Answer: B. Second Law of Thermodynamics

Explanation:

The Second Law of Thermodynamics states that entropy of an isolated system increases or remains constant. Heat spontaneously flows from hot to cold, not vice versa, establishing the direction of processes.

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Q.5 Medium Physics

A moving object has kinetic energy K. If its velocity is doubled, what will be its new kinetic energy?

A 2K

B 4K

C K/2

D K/4

Correct Answer: B. 4K

Explanation:

Kinetic energy KE = (1/2)mv². When velocity is doubled: KE' = (1/2)m(2v)² = (1/2)m(4v²) = 4 × (1/2)mv² = 4K.

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Q.6 Medium Physics

Which of the following correctly describes the photoelectric effect?

A Emission of electrons from a metal when exposed to light of sufficient frequency

B Emission of electrons from a metal when exposed to light of any frequency

C Absorption of light energy by electrons in a metal

D The bending of light around obstacles

Correct Answer: A. Emission of electrons from a metal when exposed to light of sufficient frequency

Explanation:

The photoelectric effect occurs when light of frequency greater than or equal to the threshold frequency strikes a metal surface, causing electron emission. It demonstrates the particle nature of light.

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Q.7 Medium Physics

When a spring is compressed by 0.1 m, the elastic potential energy stored is 5 J. What is the spring constant?

A 500 N/m

B 1000 N/m

C 50 N/m

D 5000 N/m

Correct Answer: B. 1000 N/m

Explanation:

Elastic potential energy E = (1/2)kx². 5 = (1/2)k(0.1)². 5 = 0.005k. k = 1000 N/m.

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Q.8 Medium Physics

A sound wave has a frequency of 440 Hz and travels at 330 m/s in air. What is its wavelength?

A 0.75 m

B 145200 m

C 0.5 m

D 770 m

Correct Answer: A. 0.75 m

Explanation:

Using v = fλ, where v = 330 m/s and f = 440 Hz. λ = v/f = 330/440 = 0.75 m.

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Q.9 Medium Physics

Two resistances of 10 Ω and 20 Ω are connected in parallel. What is the equivalent resistance?

A 30 Ω

B 6.67 Ω

C 15 Ω

D 200 Ω

Correct Answer: B. 6.67 Ω

Explanation:

For parallel resistances: 1/R = 1/R₁ + 1/R₂ = 1/10 + 1/20 = 3/20. Therefore R = 20/3 = 6.67 Ω.

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Q.10 Medium Physics

A concave mirror has a focal length of 10 cm. An object is placed 5 cm from the mirror. What type of image is formed?

A Real, inverted, magnified

B Virtual, erect, magnified

C Real, inverted, diminished

D Virtual, erect, diminished

Correct Answer: B. Virtual, erect, magnified

Explanation:

When object distance (5 cm) < focal length (10 cm), the object is between the mirror and focus. A concave mirror forms a virtual, erect, and magnified image in this case.

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