On which of the following four processes, does the functioning of a bimetallic strip depends

$(i)$ Radiation

$(ii)$ Energy conversion

$(iii)$ Melting

$(iv)$ Thermal expansion

The coefficient of linear expansion of crystal in one direction is ${\alpha _1}$ and that in every direction perpendicular to it is ${\alpha _2}$. The coefficient of cubical expansion is

A one litre glass flask contains some mercury. It is found that at different temperatures the volume of air inside the flak remains the same. ...... $cc$ is the volume of mercury in this flask if coefficient of linear expansion of glass is $9 \times 10^{-6}  /^o C$ while of volume expansion of mercury is $1.8 \times {10^4}\,/^\circ C$

Two different wires having lengths $L _{1}$ and $L _{2}$ and respective temperature coefficient of linear expansion $\alpha_{1}$ and $\alpha_{2},$ are joined end-to-end. Then the effective temperature coefficient of linear expansion is

The pressure $( P )$ and temperature $( T )$ relationship of an ideal gas obeys the equation $PT ^2=$ constant. The volume expansion coefficient of the gas will be:

When a bimetallic strip is heated, it