If p.d. across a capacitor is doubled b. halved, by what factor does the energy stored change in each case?

Explanation

`E=1/2 CV^(2)`
a. `triangleE=(1/2 C(2V)^(2))/(1/2 CV^(2)) =4"times "`
b. `triangleE=(1/2 C(V/2)^2)/(1/2 CV^(2))=1/4`