A ball of mass `1g` and charge `10^(-8) C` moves from a point `A`. Where potential is `600` volt to the point `B` where potential is zero. Velocity of the ball at the point `B` is `20 cm//s`. The velocity of the ball at the point `A` will be

Options

A. `22.8 cm//s`
B. `228cm//s`
C. `16.8 cm//s`
D. `168 cm//s`

Answer

A

Explanation

By using `(1)/(2) m(v_(1)^(2) - v_(2)^(2)) = QV`
`rArr(1)/(2) xx 10^(-3) {v_(1)^(2) - (0.2)^(2)} = 10^(-8) (600 - 0)`
`rArr v_(1) = 22.8 cm//s`