A Carnot’s Engine Whose Sink Is At A Temperature Of 300 K Has An Efficiency Of 40%. By How Much Should The Temperature Of The Source Be Increased So As To Increase The Efficiency To 60%?

Each square meter of sun’s surface radiates energy at the rate of . Assuming that Stefan’s law applies to the radiation, the temperature of sun’s surface is (Stefan’s constant )

Experimental investigations show that the intensity of the solar radiation is maximum for a wavelength 4750  in the visible region. If the surface temperature of the sun is 6000 K, what is the value of the Wien’s constantb?

The specific heat of helium at constant volume is 12.6 J mol^–1K^–1. What is the specific of hydrogen at constant volume in J mol^–1K^–1? Assume that the temperature of the gas is moderate.

The equation of state of n moles of an ideal gas is PV = nRT, where R is a constant. The SI unit for R is

A thin copper wire of length L increases its length by 1% when heated from temperature T₁ to T₂. What is the percentage change in area when a thin copper plate having dimensions  is heated from T₁ toT₂?

In Fig., curves AB and CD represent the relation between pressure P and volume V of an ideal gas. One of the curves represents an isothermal expansion and the other represents an adiabatic expansion. Which curve represents an adiabatic expansion?

One mole of an ideal gas  at absolute temperature T₁ is adiabatically compressed from an initial pressure P₁ to a final pressure P₂. The resulting temperatureT₂ of the gas is given by

A certain mass of an ideal gas at pressure P₁ is adiabatically expanded from an initial volume V₁ to a final volume V₂. The resulting pressure P₂ of the gas is given by

A Carnot’s engine working between 27^oC and 127^oC takes up 800 J of heat from the reservoir in one cycle. What is the work done by the engine?

The surface of the earth receives solar radiation at the rate of 1400 Wm ^{– 2}. The distance of the centre of the sun from the surface of the earth is  m and the radius of the sun is  m. Treating the sun as a back body, it follows from the above data that the surface temperature of the sun is about