A parallel plate capacitor has a capacitance of 60 PF, when the plates of the capacitor and separated by a distance d. if a metal plate of thickness `t=(d)/(3)` is introduced between the plates, the capacitance will be

Options

A. 60 PF
B. 40 PF
C. 90 PF
D. 75 PF

Answer

C

Explanation

`t=(1)/(3)d" "therefore d-t=(2)/(3)d and K=oo` for a metal place.
`therefore C'=(epsi_(0)A)/((1)/(oo)+(d-t)/(1))=(epsi_(0)A)/((2)/(3)d)=(3)/(2)C=90PF`