The capacitance of a parallel plate air condenser is `10muF`. When the space between the plates is filled with a liquid of dielectric constant K, the potential difference between the plates reduces to 1/5 of the original value. The value of the dielectric constant of the liquid is

Options

A. 2
B. 5
C. 10
D. 8

Answer

B

Explanation

`C=(Q)/(V)" i.e. "Cprop(1)/(V)`
`therefore (C_(2))/(C_(1))=(V_(1))/(V_(2))=5` . . (1)
and `(C_(2))/(C_(1))=(KA epsi_(0))/(d)xx(d)/(A epsi_(0)) =K` . . . (2)
From (1) and (2), K=5