Two large vertical and parallel metal plates having a separation of 1cm are connected to a DC voltage source of potential difference X. A proton is released at rest midway between the two plates. It is found to move at `45^@` to the vertical JUST after release. Then X is nearly

Options

A. `1 xx 10^(-5) V`
B. `1 xx 10^(-7) V`
C. `1 xx 10^(-9) V`
D. `1 xx 10^(-10) V`

Answer

3

Explanation

`tan 45^(@) = (qE)/(mg)`
`1 = (q(X)/(d))/(mg)`
`X = (mgd)/(q)`
`= (1.67 xx 10^(-27) xx 10 xx 10^(-2))/(1.6 xx 10^(-19))`
`= 10^(-9) V`