Thermodynamics questions with solutions

Showing 1–10 of 519 questions

• MCQmediumThermodynamics

  Two spheres of the same material have radii 1 m and 4 m and temperatures 4000 K and 2000 K respectively. The ratio of the energy radiated per second by the first sphere to that by the second is-

  Options

  • Option A

    1 : 1

  • Option B

    16 : 1

  • Option C

    4 : 1

  • Option D

    1 : 9

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• MCQmediumThermodynamics

  A rod of length 'λ' and cross-section

  

  'A' is used to melt a piece of ice as shown.

  Now if the rod broken into two equal parts and is arranged as shown. Time taken to melt ice in second case becomes.

  

  Options

  • Option A

    Half

  • Option B

    One-forth

  • Option C

    Twice

  • Option D

    Four times

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• MCQmediumThermodynamicsThermodynamic Processes, P-V Diagrams and Work Done

  A sample of gas at temperature T is adiabatically expanded to double its volume. The work done by the gas in the process is: [γ = 3/2]

  Options

  • Option A

    TR(√2 - 2)

  • Option B

    (T/R)(√2 - 2)

  • Option C

    (R/T)(2 - √2)

  • Option D

    RT(2 - √2)

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  JEE Mains1 February 2023Shift 1Morning Shift

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• MCQeasyThermodynamicsHeat, Specific Heat Capacity, Latent Heat and Calorimetry

  Which relation correctly represents Celsius temperature C and Fahrenheit temperature F?

  Options

  • Option A
    
  • Option B
    
  • Option C
    
  • Option D
    

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  JEE Mains 2025 24 Jan Evening Shift

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• NumericeasyThermodynamicsHeat, Specific Heat Capacity, Latent Heat and Calorimetry

  A water heater of power 2000 W is used to heat 2 kg of water from 10°C to 60°C. Specific heat capacity of water is 4200 J kg⁻¹ K⁻¹ and efficiency of heater is 70%. Time required is ______ s.

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  JEE Mains31 January 2023Shift 2Evening Shift

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• Multi-correctmediumThermodynamics

  A gas expands such that its initial and final temperature are equal. Also, the process followed by the gas traces a straight line on the P-V diagram :

  Select all that apply

  • Option A

    The temperature of the gas remains constant throughout.

  • Option B

    The temperature of the gas first increases and then decreases

  • Option C

    The temperature of the gas first decreases and then increases

  • Option D

    The straight line has a negative slope.

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• MCQmediumThermodynamics

  A black body is at 2880 K. Let U₁ be the energy emitted between 499 and 500 nm, U₂ between 999 and 1000 nm, and U₃ between 1499 and 1500 nm. Wien's constant is b=2.88×10⁶ nm K. Which statement is correct?

  Options

  • Option A

    U₁=0

  • Option B

    U₃=0

  • Option C

    U₁>U₂

  • Option D

    U₂>U₁

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• MCQmediumThermodynamics

  Two rectangular blocks, having identical dimensions, can be arranged either in configuration I or inconfigurationII as shownin the figure. One of the blocks has thermal conductivity k and the other 2k. The temperature difference between the ends along the x-axis is the same in both the configurations. It takes 9s to transport a certain amount of heat from the hot end to the cold end in the configuration I. The time to transport the same amount of heat in the configuration II is :-

  

  Options

  • Option A

    2.0 s

  • Option B

    3.0 s

  • Option C

    4.5 s

  • Option D

    6.0 s

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• MCQmediumThermodynamics

  A continuous flow water heater (geyser) has an electrical power rating = 2 kW and efficiency of conversion of electrical power into heat = 80%. If water is flowing through the device at the rate of 100 cc/sec, and the inlet temperature is 10°C, the outlet temperature will be

  Options

  • Option A

    12.2°C

  • Option B

    13.8°C

  • Option C

    20°C

  • Option D

    16.5°C

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• MCQmediumThermodynamics

  A lead ball at 30°C is dropped from a height of 6.2 km. The ball is heated due to the air resistance and it completely melts just before reaching the ground. The molten substance falls slowly on the ground. Calculate the latent heat of fusion of lead. Specific heat capacity of lead = 126 J kg⁻¹°C⁻¹ and melting point of lead = 330°C. Assume that any mechanical energy lost is used to heat the ball. Use g = 10 m s⁻².

  Options

  • Option A

    6×10³ J kg⁻¹

  • Option B

    1.2 ×10⁴ J kg⁻¹

  • Option C

    1.8 ×10⁴ J kg⁻¹

  • Option D

    2.4 ×10⁴ J kg⁻¹

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