Question

The magnitude of point charge due to which the electric field 30 cm away has the magnitude 2 NC^-1 will be ____________.

Options

• 2 x 10^-11 C

• 3 x 10^-11 C

• 5 x 10^-11 C

• 9 x 10^-11 C

Answer 1

The magnitude of point charge due to which the electric field 30 cm away has the magnitude 2 NC^-1 will be 2 x 10^-11 C.

Explanation:

`"E" = "kq"/"r"^2`

`therefore "q" = "Er"^2/"k"`

` = (2 xx (0.3)^2)/(9 xx 10^2)`

`= (2 xx 9 xx 10^-2 xx 10^-9)/9`

`therefore "q" = 2 xx 10^-11 "C"`