A system is shown in the figure. The time period for small oscillations of the two bolcks will be :-

Options

A. `4.5 xx10^(-6) J`
B. `2.25 xx10^(-6) J`
C. Zero
D. `9 xx10^(-6) J`

Answer

B

Explanation

`Q= 900 xx10^(-12) xx100 =9 xx10^(-8)C`
`U_i = (Q^2)/(2C_1)=(9xx9 xx10^(-16))/(2 xx900 xx10^(-12))=4.5 xx10^(-6)J`
`U_f = Q^2/(2C_1+C_2)=(9 xx9xx10^(-16))/(2 xx 1800 xx10^(-12))=2.25 xx10^(-6) J`
Loss of energy `=U_i -U_f = 2.25 xx10^(-6) J`