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JEE Physics

Physics questions for JEE Main — Mechanics, Electrostatics, Optics, Modern Physics.

301 Q 9 Topics Take Test
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Difficulty: All Easy Medium Hard 261–270 of 301
Topics in JEE Physics
Q.261 Easy Thermodynamics
In an isochoric process for an ideal gas, what is the relationship between pressure and temperature?
A P/T = constant
B P×T = constant
C P = T
D P/T² = constant
Correct Answer:  A. P/T = constant
EXPLANATION

For isochoric process (constant volume): PV = nRT with V constant gives P/T = nR/V = constant (Gay-Lussac's Law)

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Q.262 Easy Thermodynamics
What is the relationship between Cₚ and Cᵥ for an ideal gas?
A Cₚ = Cᵥ + R
B Cₚ = Cᵥ - R
C Cₚ = 2Cᵥ
D Cₚ/Cᵥ = constant
Correct Answer:  A. Cₚ = Cᵥ + R
EXPLANATION

Mayer's relation: Cₚ - Cᵥ = R for one mole of ideal gas, hence Cₚ = Cᵥ + R

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Q.263 Easy Thermodynamics
For an ideal gas, internal energy depends on:
A Only temperature
B Only volume
C Both pressure and volume
D Pressure, volume, and temperature equally
Correct Answer:  A. Only temperature
EXPLANATION

For an ideal gas, internal energy U depends only on temperature (U = nCᵥT), not on pressure or volume independently

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Q.264 Easy Thermodynamics
What is the first law of thermodynamics?
A ΔU = Q - W
B ΔU = Q + W
C Q = W + ΔU
D W = ΔU + Q
Correct Answer:  B. ΔU = Q + W
EXPLANATION

The first law states: ΔU = Q + W, where ΔU is change in internal energy, Q is heat absorbed, and W is work done on the system

Test
Q.265 Easy Thermodynamics
A Carnot engine operates between temperature reservoirs of 500 K and 300 K. What is its maximum efficiency?
A 0.40 or 40%
B 0.60 or 60%
C 0.33 or 33%
D 0.50 or 50%
Correct Answer:  A. 0.40 or 40%
EXPLANATION

Carnot efficiency: η = 1 - (Tc/Th) = 1 - (300/500) = 1 - 0.60 = 0.40 or 40%

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Q.266 Easy Mechanics
An elevator accelerates upward at 2 m/s². A person of mass 60 kg stands in it. What is the normal force exerted by the floor on the person? (g = 10 m/s²)
A 600 N
B 660 N
C 720 N
D 540 N
Correct Answer:  C. 720 N
EXPLANATION

N - mg = ma (upward acceleration), so N = m(g + a) = 60(10 + 2) = 60 × 12 = 720 N

Test
Q.267 Easy Mechanics
A body of mass 2 kg moves in a circular path of radius 0.5 m with constant speed. If the centripetal acceleration is 8 m/s², what is the centripetal force required?
A 16 N
B 8 N
C 4 N
D 2 N
Correct Answer:  A. 16 N
EXPLANATION

Centripetal force F = ma_c = 2 × 8 = 16 N. This is the net force directed toward the center of circular motion.

Test
Q.268 Easy Mechanics
A projectile is launched at an angle of 45° with initial velocity 20 m/s. Neglecting air resistance, what is the maximum height reached? (g = 10 m/s²)
A 10 m
B 20 m
C 5 m
D 15 m
Correct Answer:  A. 10 m
EXPLANATION

At 45°, vertical component = 20sin(45°) = 10√2 m/s. Using v² = u² - 2gh, at max height v=0: h = u²/(2g) = (10√2)²/(2×10) = 200/20 = 10 m

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Q.269 Easy Mechanics
A particle undergoes SHM with amplitude A = 0.5 m and angular frequency ω = 4 rad/s. What is its maximum velocity?
A 1 m/s
B 2 m/s
C 4 m/s
D 8 m/s
Correct Answer:  B. 2 m/s
EXPLANATION

Maximum velocity in SHM = ωA = 4 × 0.5 = 2 m/s

Test
Q.270 Easy Mechanics
A particle experiences three forces: F₁ = 3i N, F₂ = 4j N, and F₃ = -3i - 4j N. What is the net force magnitude?
A 0 N
B 5 N
C 7 N
D 10 N
Correct Answer:  A. 0 N
EXPLANATION

Net force = (3-3)i + (4-4)j = 0i + 0j = 0 N. The magnitude is 0 N.

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