Question

A conducting sphere of radius 0.104 m has an unknown charge. If the electric field at 0.20 m from the centre of the sphere is 1.5 x 10³ NC^-1 and points radially inward, what is the electric flux?

Options

• 753.7 Nm² C^-1

• - 753.7 Nm² C^-1

• 669.8 Nm² C^-1

• 667.8 Nm² C^-1

Answer 1

- 753.7 Nm² C^-1

`"E" = 1/(4pi epsilon_0) "q"/"r"^2`

`therefore "q" = (1.5 xx 10^3 xx 0.04)/(9 xx10^9)`       ......(∵ r = 0.2 m)

= - 6.67 x 10^-9 C

(-ve sign indicates field is inward)

`phi = "q"/epsilon_0 = (-6.67 xx 10^-9)/(8.85 xx 10^-12)`

`= -753.7 "Nm"^2 "C"^-1`