A pith ball carrying a charge of `3 xx 10^(-10) C` is suspended by an insulated thread of length `50 cm`.When a uniform electric filed is applied in a horizontal direction , the ball is found to deflect by `2 cm` from the vertical. If the mass of the ball is `0.5 gm` , the intensity of the electric field is :

Options

A. `6.6 xx 10^(5) N//C`
B. `3.3 xx 10^(5) N//C`
C. `9.9 xx 10^(5) N//C`
D. `1.1 xx 10^(5) N//C`

Answer

1

Explanation

`tan theta = (qE)/(mg)`
From geometry : `tan theta ~= sin theta = (d)/(L) = (2)/(50) = (1)/(25)`
`(qE)/(mg) = (1)/(25)`
`E = (mg)/(25 q) = (0.5 xx 10^(-3) xx 10)/(25 xx 3 xx 10^(-10)) = (1)/(15) xx 10^(7)`
`= 0.066 xx 10^(7) = 6.6 xx 10^(5) N//C`