## Question

### Solution

Correct option is

5803 K

Let R be the radius of the sun and let r be the radius of the earth’s orbit round the sun. If the surface temperature of the sun is T (in kelvin), the energy emitted per second by the surface of the sun = , where is Stefan’s constant whose value is  Now the area of the spherical surface of radius  Therefore, energy received per second by a unit area of the earth’s surface is

Which gives

or                  T = 5803 K

#### SIMILAR QUESTIONS

Q1

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?

Q2

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.

Q3

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

Q4

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?

Q5

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?

Q6

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

Q7

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

Q8

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

Q9

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%?

Q10

What is the SI unit of the Boltzmann’s constant?