The capacity and the energy stored in a parallel plate condenser with air between its plates are respectively `C_(0)` and `W_(0)`. If the air is replaced by glass (dielectric constant `= 5`) between the plates, the capacity of the plates and the energy stored in it will respectively be

Options

A. `5C_(0),5W_(0)`
B. `5C_(0),(W_(0))/(5)`
C. `(C_(0))/(5),5W_(0)`
D. `(C_(0))/(5),(W_(0))/(5)`

Answer

B

Explanation

When a dielectric `K` is introduced in a parallel plate condenser its capacity becomes `K` times. Hence
`C' = 5C_(0)`. Energy stored `W_(0) = (q^(2))/(2C_(0))`
`:. W' = (q^(2))/(2C') = (q^(2))/(2 xx 5C_(0)) rArr W' = (W_(0))/(5)`