Case : Read the passage and answer the question(s).

In a parallel plate air capacitor having plate separation 0.05mm, an electric field of 4X10⁴ V/m is established between the plates. After the removal of the battery a metal plate of thickness t = 0.02 mm is inserted between the plates of the capacitor. 

What is the potential difference across capacitor after the introduction of metal plates?

1200 V

V = E x d

E = 4 x 10⁴ V/m ; d = 0.05 mm

V = 2000 V

Q = C V = 2000 C ;

C' = C' = \(\frac{C}{1 - t/d}\) = \(\frac{C}{1 - 0.02/0.05}\) = \(\frac{5}{3}\) C ;

Also, Q = C' V' =  \(\frac{5}{3}\) C V' ;

C V = C' V' ⇒ V' = 1200 V