Two large vertical and parallel metal plates having a separation of 1 cm 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

C

Explanation

Net force is at `45^(@)` from vertical.
` therefore qE = mg `
` or (QE)/(d) = mg " " ( therefore E = (x)/(d))`
` or X = (m g d)/( q) = ((1.67xx 10^(-27))(9.8) (10^(-2))/((1.6 xx 10^(-19)) = 1 xx 10^(-19) V`