A capacitance balance is shown in the figure. The balance has a block pulley system attached on one side and a capacitor that has a variable gap width on the other side. Assume upper plate of the capacitor has negligible mass. When the separation between the plate is `1/(sqrt(5))` meter, the attractive force between the plates balances the pulley block system. Then find value of `V_(0)` in volts (EMF of battery). (Take area of the plate `=20/(3epsilon_(0))m^(2)`)

Answer

4

Explanation

Tension in upper rope `=800/3 N`
By balancing Torque about `'O'`
`800/3=(V_(0)^(2) epsilon_(0)A)/(2d^(2))=(V_(0)^(2)epsilon_(0)20)/(2(1/5)3epsilon_(0))`
`V_(0)=4` Volts