Q.

A parallel plate air capacitor has a capacitance C. When it is half filled as shown in figure with a dielectric constant K = 5, the percentage increase in the capacitance is ____. [2026]

1 33.34  
2 66.67  
3 200  
4 400  

Ans.

(2)

Initial capacitance:   Ci=Aε0d=C

Final capacitance:

C1=Aε0×5d2=10C  and  C2=Aε0d2=2C

Cf=C1C2C1+C2=10×210+2C=53C

% increase=53C-CC×100=66.67