and B are two points on a uniform metal ring whose centre is C. The angle A and are maintained at two different constant temperatures. When  the rate of total heat flow from  A to B is 1.2 W. When  this rate will be:


Correct option is

1.6 W


Let  R = total thermal resistance of the ring


For  two sections of resistance R/2 each are in parallel. So equivalent resistance = R/4.

 Rate of total heat flow 








One mole of an ideal mono-atomic gas is heated at a constant pressure of one atmosphere from 0oC to 100oC. The heat taken from the source is:


Three moles of an ideal mono-atomic gas perform a cycle as shown in figure. The gas temperatures in different states are  The work done by the gas during the cycle will be:



Equal volumes of water and alcohol when put in similar calorimeters take 100 sec and 74 sec respectively to cool from 50oC to 40oC. The thermal capacity of each calorimeter is numerically equal to the volume of either liquid. The specific gravity of alcohol is 0.8. If the specific heat capacity of water is 1 cal/g, the specific heat capacity of alcohol will be:


During an adiabatic process at constant pressure, the temperature and volume of a gas are found to vary according to the relation TV0.4 constant. The gas should be:


A system S receives heat continuously from an electric heater of power 10 W. The temperature of S becomes constant at 50oC when the surrounding temperature is 20oC. After the heater is switched off, S cools from 35.1oC to 34.9oC in 1 minute. The heat capacity of S is:


A body with an initial temperature  is allowed to cool in a surrounding which is at a constant temperature of   Assume that Newton’s law of cooling is obeyed. Let k = constant. The temperature of the body after time  is best expressed by:


The power radiated by a black body is P, and it radiates maximum energy around the wavelength  If the temperature of the black body is now changed so that it radiates maximum energy around a wavelength, the power radiated by it will increase by a factor of:


The solar constant for a planet is S. The surface temperature of the sun isK. The sun subtends an angle  at the planet:



The temperature of an isolated black body falls from T1 to T2 in time t. LetC be a constant;



A mixture of n1 moles of mono-atomic gas and n2 moles of diatomic gas has