A charge + 2 `mu`C is placed at x = 0 and a charge of - 32 `mu`C at x = 60 cm where must a third charge + Q be placed on the x-axis such that it experiences no force? The distance of the point is

Options

A. 20 cm left
B. 20 cm right
C. 30 cm left
D. 30 cm right

Answer

(a)

Explanation

Force applied by `q_(1)` is,
`F_(1) = kQq_(1)/x^(2) (along AP)`
Force applied by `q_(2)` is,
`F_(2) = kQq_(2)/(x+60)^(2) (along PA)`
Force `F_(1)` and `F_(2)` are in opposite direction
Hence ,for zero force on Q
`F_(1) = F _(2)`
` kQq_(1)/x^(2) = kQq_(2)/(x+60)^(2)`
`rArr 2/x^(2) = 32/(x + 60)^(2)`
`rArr ` x + 60 = 4x
`:. ` x = 20 cm