Thermal Properties Of Matter

If is the volume of glass flask, mercury and of air in it

Now as with change in temperature volume of air remains constant, the expansion of mercury will be equal to that of the glass flask,
ie,
or
( as )
or

A cooking pot should absorb minimum heat and conduct maximum heat A cooking pot should easily transfer heat to its content (high conductivity) and not requiring too much heat to get to the right temperature (low specific heat), because it would reduce efficiency, since you would spend more energy heating the pot instead of the content.

Answer (c) Doppler effect

We know, or,

Here ,

or
or,

Woollen clothes keep the body warm because they do not allow heat to flow out of the body.

Answer (c)

Let be the temperature of the junction of the two rods and be the area of cross-section of each rod. Under steady condition, the heat conducted per second through rod 1 is equal to the heat conducted per second through rod 2,
...(i)
where L is the length of each rod.
or
or ....(ii)
Put equation (ii) in (i), we get

...(iii)
If is the equivalent thermal conductivity of the two rods, then
....(iv)
From (iii) and (iv)
or

According to Wein's displacement law
= constant or,
Here, at temperature at temperature
or

As , (energy radiated per unit area per second)
...(i)
Also, according to Wein's displacement law,
...(ii)
From eqn (i) and (ii),

Here ,
So,

Under steady condition, heat current through metallic slab of conductivity is same that in other slab of conductivity

or

So,
or ,
\or ,
Also,

...(i)
Let equivalent thermal conductivity of bi-metallic slab be Kand length of bi-metalic slab =
So, ....(ii)
From eqn (i) and (ii)
or,

Let be temperature on Fahrenheit scale corresponding to on Celsius scale. Then or