Question

Infinite sheet carrying surface charge density sigma = - 1 MuC/m^2 is in y-z plane. A point charge q= +8pie MuC is located on x-axis at point (1,0) one meter from the origin. Find the forces acting on the charge q and on the charged plate. Find a coordinate or coordinates on the x-axis for which the net electric field zeroes.

Answer 1

a)

Field due to infinite sheet carrying surface,

E = sigma / 2e0

E = (1 x 10^-6) / (2 x 8.854 x 10^-12 ) =56471.65 N/C towards the sheet

and force = q E = 8 x pi x 10^-6 x 56471.65

= 1.42 N toward the sheet

b) field due to +ve point charge is always away from it.

so point where field is zero will be x > 1

suppose coordinate is x .

then kq/d^2 - 56471.65 = 0

(9 x 10^9 x 8x pi x 10^-6) / ((x - 1)^2) = 56471.65

x - 1 = 2 m

x = 3 m ............Ans