Question

two charges of magnitude -2 q and + Q are located at point ( a,0) and (4a,) respectively what is the electric Flux due to these charges through a sphere of radius '3a' with its centre at the origin. plz answer me fast

Answer 1

q₁ = charge placed on x-axis at distance "a" from origin = - 2 q

q₂ = charge placed on x-axis at distance "4a" from origin = Q

r = radius of sphere whose center is at origin = 3 a

hence all charges which are at distance smaller than radius of sphere , lies inside the sphere . hence

Q' = charge enclosed by the sphere = q₁ = - 2 q

according to gauss;s law

Electric flux = charge enclosed /ε

Φ = Q' /ε

Φ =  - 2 q /ε

Φ =  - 2 q /(8.85 x 10⁻¹²)

Φ = - 2.26 x 10¹¹ q