Estimate the percentange change of the energy stored in a parallel plate capacitor, if the separation between its plates is reduced by 10%, keeping the voltage of the charging source unchanged?

Explanation

Let d= initial separation between the plates.
Final separation, `d' = d - (10%" of "d) = d-(d)/(10)= 0.9d`
Initial and final values of the energy stored in the capacitor are,
`U = (1)/(2)CV^2 = (1)/(2)(in_0 alpha)/(d)V^2 " and " U' = (1)/(2)*(in_0alpha)/(0.9d)V^2`
Percentage increase of energy,
`(U'-U)/(U)xx100 = ((U')/(U)-1)xx100= ((1)/(0.9)-1)xx100`
`(0.1)/(0.9)xx100 = (100)/(9) = 11.1%`.