Thermal Propert...

Select the correct option given below:
In order that the heat flows from one part of solid to another part,what is required. ?

A steel metre scale is to be ruled so that the millimetre intervals are accurate within about $$5\times { 10 }^{ -5 }mm$$ at a certain temperature. The maximum temperature variation allowable during the ruling of the millimetre marks is ($$\alpha$$ for steel $$=11\times { 10 }^{ -6 }_{  }\quad ^{ o }{ { C }^{ -1 } }$$) 

If the temperature of the Sun were to increase from $$T$$ to $$2T$$ and its radius from $$R$$ to $$2R$$. The ratio of power radiated by it would become:

Clear nights are colder than cloudy nights because of

In which of the following process convection does not take place primarily?

Select the correct option given below:
Which of the following graphs correctly shows variation of coefficient of volume expansion of copper as a function of temperature?

One end of a $$0.25m$$ long metal bar is in steam and the other is in contact with ice .If $$12g$$ of ice melts per minute, then the thermal conductivity of the metal is (Given cross section of the bar$$=5\times 10^{-4}m^{2}$$ and latent heat of ice is $$80\,cal \,g^{-1}$$)

A disc of mass 500 g and radius 10 cm rotates about a fixed vertical axis passing through its centre, with an angular velocity 3 rad/s. A ring of same mass and radius is gently placed on it coaxially. The heat evolved after sufficient time is:

A wall is made of equally thick layers A and B of different materials. Thermal conductivity of A is twice that that of B . In the steady state, the temperature difference across the wall is $$36^o C$$. The temperature difference across the layers A is:

The temperature of $$100$$g of water is to be raised form $$24^o$$C to $$90^o$$C by adding steam to it. Calculate the mass of the steam required for this purpose.