Three large plates are arranged as shown. How much charge will flow through the key k if it is closed?

Options

A. `(5Q)/(6)`
B. `(4Q)/(3)`
C. `(3Q)/(2)`
D. None of these

Answer

A

Explanation

After key closed
`implies 3Q-y=y implies y=(3Q)/(2)`
`(x)/(c)=((-2Q-x)/(c//2))`
`implies x=-4Q-2x implies x=-4Q//3`
`(3Q)/(2)|(-4Q)/(3)(4Q)/(3)|(2Q)/(3)" "(-2Q)/(3)|(3Q)/(2)`
Hence charge will flow `=(30)/(2)-(2Q)/(3)=(5Q)/(6)`.