The capacitance of an air filled parallel plate capacitor is `10 muF`. The separation between the plates is doubled and the space between the plates is then filled with wax giving the capacitance a new value of `40 xx 10^(-12)` farads. The dielectirc consatnt of wax is

Options

A. `12.0`
B. `10.0`
C. `8.0`
D. `4.2`

Answer

C

Explanation

`C_(1) = (epsilon_(0)A)/(d)` and `C_(2) = (K epsilon_(0)A)/(2d)`
`rArr (C_(2))/(C_(1)) = (K)/(2) rArr (40 xx 10^(-12))/(10 xx 10^(-12)) = (K)/(2) rArr K = 8`