Two large vertical and parallel metal plates having a separation of...

Two large vertical and parallel metal plates having a separation of \( 1 \mathrm{~cm} \) are connected to a DC voltage source of potential difference \( \mathrm{X} \). A proton is released at rest midway between the two plates. It is found
\( \mathrm{P} \) to move at \( 45^{\circ} \) to the vertical JUST after release. Then \( \mathrm{X} \) is nearly
(A) \( 1 \times 10^{-5} \mathrm{~V} \)
(B) \( 1 \times 10^{-7} \mathrm{~V} \)
(C) \( 1 \times 10^{-9} \mathrm{~V} \)
(D) \( 1 \times 10^{-10} \mathrm{~V} \)
W.