Question

Two-point charges of + 0.2 µµC and -0.2 µµC are separated by 1 o8 m. What is the value of the electric field at an axial point at a distance of 0.1 m from their mid-point?

Options

• 3.9 x 10^-8 NC^-1

• 3.2 x 10^-8 NC^-1

• 3.6 x 10^-8 NC^-1

• 3.4 x 10^-8 NC^-1

Answer 1

3.6 x 10^-8 NC^-1

Explanation:

For r >> l,

E = `1/(4piepsilon_0) (2_p)/"r"^3 = 1/ (4piepsilon_0) (2"q"(2l))/"r"^3`

∴ E = ` (9xx 10^9 xx 2xx 0.2 xx 10^-12 xx 10^-8)/(0.1)^3 "NC"^-1`

= ` 3.6 xx 10^-8  "NC"^-1`