Assertion: A parallel plate capacitor is connected across battery through a key. A dielectric slab of constant `K` is introduced between the plates. The energy which is stored becomes`K` times.
Reason: The surface density of charge on the plate remains constant or uncharged

Options

A. If both assertion and reason are true and reson is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assertion and reason both are false.

Answer

C

Explanation

In the givrn case `V = V_(0)` (constant)
Energy stored in the capacitor `= (1)/(2)CV^(2)`
`Crarr KC`, so energy stored will become `A` times
`Q = CV`, so `Q` will become `K` timess
`:.` Surface charge density `sigam' = (Kq)/(A) = K sigam_(0)`.