A cylindrical tube of uniform cross-sectional area A is fitted with two air tight frictionless pistons.

The pistons are connected to each other by a metallic wire. Initially, the pressure of the gas is p₀ and temperature is T₀, atmospheric pressure is also p₀. Now, the temperature of the gas is increased to 2T₀, the tension in the wire will be

Volume of the gas V is constant.

$\therefore \mathrm{p} \propto \mathrm{T},$ i.e. pressure will be doubled when temperature is doubled.

$\therefore$                                   p = 2p₀

Now, let F be the tension in the wire. Then, equilibrium of anyone piston will give

                                       $F = (p-p_0)A$

                                          $= (2p_0-p_0)A$

                                           = p₀A