Prove n =1 for pv^n=C, when temperature is constant

[nu_hash]

Homework Statement

Show that an isothermal process can be regarded as a special case of a polytropic process and deduce what value of n applies in this case.

Homework Equations

$P_{1}V_{1}^n = const$

The Attempt at a Solution

$P_{1}V_{1}^n = mRT_{1}$
$P_{2}V_{2}^n = mRT_{1}$

(since temperature is constant $T_{2} = T_{1}$)

therefore:
$P_{1}V_{1}^n = P_{2}V_{2}^n$

but i don't think this proves that n=1 for a isothermal process

 

[dikmikkel]

Edit: What I wrote was nonsense sorry.