Two metal plates having a potential difference of 800 V are 0.02 m apart horizontally. A particle of mass `1.96 xx 10^(-15)` kg is suspended in equilibrium between the plates. If e is the elementary charge, the charge on the particle is

Options

A. (A) 6e
B. (B) e
C. (C) 8e
D. (D) 3e

Answer

D

Explanation

For steady position weight = electric force
`therefore mg = QE`
`therefore mg = "ne"E`
`therefore "ne" = (mg)/E = (mgd)/V [therefore E =V/d]`
`=(1.96 xx 10^(-15) xx 9.8 xx 0.02)/800 = 0.00048 xx 10^(-15)`
`therefore Q = 3 xx 1.6 xx 10^(-19)`
`therefore Q = 3e (therefore 1.6 xx 10^(-19) C =e)`