AIIMS Physics Thermodynamics Class 11 Questions

For a refrigerator, heat absorbed from source is 800 J and heat supplied to sink is 500 J then the coefficient of performance is

A Carnot engine works between 27°C and 127°C. Heat supplied by the source is 500 J. then heat ejected to the sink is

If sink and source temperature of a refrigerator are 4°C and 15°C respectively. Then efficiency of refrigerator is:

In an isothermal process 2 water drops of radius 1 mm are combined to form a bigger drop. Find the energy change in this process if $\text{T} = 0.1\text{ N/m}$

If 7 gm $\text{N}_2$ is mixed with 20 gm Ar, there $\text{C}_\text{p}/\text{C}_\text{v}$ of mixture will be:

The dimensional formula of Boltzmann's constant is:

A disc of radius 20 cm and mass half kg is rolling on an inclined plane. Find out friction force so that disc performs pure rolling.

In an Isobaric process, the work done by a di-atomic gas is 10J, the heat given to the gas will be

An ideal gas initially at pressure 1 bar is being compressed from 30 m³ to 10 m³ volume and its temperature decreases from 320 K to 280 K. then find final pressure of gas

Distance between sun and Earth is 2×10⁸ km, temperature of sun 6000 K, radius of sun 7×10⁵ km. If emissivity of the earth is 0.6, find out the temperature of the earth in thermal equilibrium

Assertion: $_{1}^{3}\text{H}$ isotope does not undergo fusion of the type $_{1}^{3}\text{H} + _{1}^{2}\text{H} \rightarrow$ as it is rarely found in nature. Reason: $_{1}^{3}\text{H}$ has half life of $\approx 12$ years.

Determine coefficient of performance of given temperature limit. $$T_1 = 27^\circ\text{C}\ \text{[outside fridge]}$$ $$T_2 = -23^\circ\text{C}\ \text{[inside fridge]}$$

Find $\gamma$ for the mixture of $11\text{ gmCO}_2$ and $14\text{ gmN}_2$?

$\text{N}_2$ gas is heated from 300 K temperature to 600 K through an isobaric process. Then find the change in entropy of the gas. (n=1mole)

Assertion : Coefficient of performance in refrigerator may be greater than one. Reason : Heat extracted from lower temperature reservoir.

Calculate radiation power for sphere whose temperature is 227°C and radius 2 m and emissivity 0.8.

Determine efficiency of carnot cycle if in adiabatic expansion volume 3 times of initial value and $\text{r} = 1.5$

The two ends of a rod of length L and a uniform cross-sectional area A are kept at two temperatures T₁ and T₂ (T₁ > T₂). The rate of heat transfer, dQ/dt, through the rod in a steady state is given by:

The temperature of food material in refrigerator is 4°C and temperature of environment is 15°C. If carnot cycle is used in its working gas, then find its carnot efficiency.

A gun of mass $10\text{ kg}$ fires 4 bullets per second. The mass of each bullet is $20\text{ g}$ and the velocity of the bullet when it leaves the gun is $300\text{m/s}$. The force required to hold the gun while firing is

A system is given 300 calories of heat and it does 600 joules of work. How much does the internal energy of the system change in this process? (J = 4.18 Joules/cal)

Assertion : $\text{P}$ v/s $\frac{1}{\text{V}}$ graph is straight line for adiabatic process. Reason : $\text{PV} =$ constant for adiabatic process.

Assertion: Vibrational degree of freedom of a di-atomic gas molecule appears at very high temperature. Reason: di-atomic gas has two vibrational degree of freedom in one direction.

Two cylinders of equal size are filled with equal amount of ideal diatomic gas at room temperature. Both the cylinders are fitted with pistons. In cylinder A the piston is free to move while in B position is fixed. When same amount of heat is supplied to both the cylinders, the temperature of the gas cylinder A raises by 30 K. What will be the rise in temperature of the gas in cylinder B.

Assertion : In adiabatic process work is independent of path. Reason : In adiabatic process work done is equal to negative of change in internal energy.

Assertion: Air quickly leaking out of a balloon becomes cooler. Reason: The leaking air undergoes adiabatic expansion.

Assertion: The ratio $\frac{\text{C}_\text{v}}{\text{C}_\text{p}}$ for a monoatomic gas is less than for a diatomic gas. Reason: The molecules of a monoatomic gas have more degrees of freedom than those of a diatomic gas.

Assertion : Water at the foot of the water fall is always at different temperature from that at the top. Reason : The potential energy of water at the top is converted into heat energy during falling.

Assertion: Reversible systems are difficult to find in real world. Reason: Most processes are dissipative in nature.

A closed vessel explodes at 15 atm pressure. If temperature of the vessel is 300 K at 10 atm pressure then find at what temperature will the vessel explodes.

If the coefficient of performance of a refrigerator is $\beta$ and the heat given to the surroundings is $Q_2$, then what is the heat absorbed?

A solid substance is at 30°C. To this substance heat energy is supplied at a constant rate. Then temperature versus time graph is as shown in the figure. The substance is in liquid state for the portion (of the graph)

A diatomic gas which has initial volume of 10 liter is isothermally compressed to 1/15^{th} of its original volume where initial pressure is 10⁵ Pascal. If temperature is 27°C then find the work done by gas.

The black body spectrum of an object O₁ is such that its radiant intensity (i.e. intensity per unit wavelength interval) is maximum at a wavelength of 200 nₘ. Another object O₂ has the maximum radiant intensity at 600 nₘ. The ratio of power emitted per unit area by source O₁ to that of source O₂ is

If 1 cm³ of water is vaporized (latent heat of vaporization = 5.40 cal/g°C) at P = 1 atm. If the volume of steam formed is 1671 cm³ calculate increase internal energy.

The correct unit of thermal conductivity is

The molar specific heat of a gas as given from the kinetic theory is \( \frac{5}{2} R \). If it is not specified whether it is Cₚ or Cᵥ, one could conclude that the molecules of the gas

If $1\text{ cm}^3$ of water is vaporized (latent heat of vaporization = $540\text{ cal/g}$) at $P = 1\text{ atm}$. If the volume of steam formed is $1671\text{ cm}^3$, calculate the increase in internal energy.

A body cools from 50.0°C to 49.9°C in 5 s. How long will it take to cool from 40.0°C to 39.9°C? Assume the temperature of surrounding to be 30.0°C and Newton’s law of cooling to be valid

A Carnot engine whose efficiency is 50% has an exhaust temperature of $500\text{ K}$. If the efficiency is to be 60% with the same intake temperature, the exhaust temperature must be

One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, the final temperature of gas will be

Assertion : In adiabatic process change in internal energy is equal to work done on gas. Reason : In adiabatic process no heat exchange with surrounding

Assertion (A) If there is no external torque on a body about its centre of mass, then the velocity of the centre of mass remains constant. Reason (R) The linear momentum of an isolated system remains constant.

Assertion: Specific heat of a body is always greater than its thermal capacity. Reason: Thermal capacity is the heat required for raising temperature of unit mass of the body through unit degree.

Assertion: Zeroth law of thermodynamics explains the concept of energy. Reason: Energy does not depends on temperature.

Assertion: Surface tension decreases with increase in temperature. Reason: On increasing temperature kinetic energy increases and intermolecular forces decreases.

Assertion : Falling raindrops acquire a terminal velocity. Reason : A constant force in the direction of motion and a velocity dependent force opposite to the direction of motion, always result in the acquisition of terminal velocity.

Assertion: Energy of an isolated particles system is constant. Reason: Isolated system do not allow exchange of energy.

Assertion: Each vibrational mode gives two degrees of freedom. Reason: By law of equipartition of energy, the energy for each degree of freedom in thermal equilibrium is 2kₓT.

Assertion: The efficiency of a reversible engine is maximum. Reason: In such a device no dissipation of energy takes place.