Q.

The distance between two plates of a capacitor is d and its capacitance is C1, when air is the medium between the plates. If a metal sheet of thickness 2d3 and of the same area as the plates is introduced between the plates, the capacitance of the capacitor becomes C2. The ratio C2C1 is               [2023]

1 2 : 1  
2 4 : 1  
3 3 : 1  
4 1 : 1  

Ans.

(3)

Kmetal sheet=, t=2d3

C1=ε0Ad

C2=ε0Ad-t+tk=ε0Ad-2d3+0=3C1

C2C1=3