Question

Three charges – q₁ + q₂ and – q₃ are placed as shown in figure. The x component of the force on – q₁ is proportional to ……..

(A) (q₂/b²) – (q₃/a²) sinθ

(B) (q₂/b²) – (q₃/a²) cosθ

(C) (q₂/b²) + (q₃/a²) sinθ

(D) (q₂/b²) + (q₃/a²) cosθ

Answer 1

The correct option (C) (q₂/b²) + (q₃/a²)sinθ

Explanation:

Force on – q₁ due to q₂ is F₁₂ = [(kq₁q₂)/b²] along axis.

Force on – q₁ due to – q₃ is F₁₃ = [(kq₁q₃)/a²] at angle θ in negative y axis.

∴ X component of force on – q₁ is F_x = F₁₂ + F₁₃ sinθ

i.e. F_x = kq₁[(q₂/b²) + (q₃/a²) sinθ]

i.e. F_x ∝ (q₂/b²) + (q₃/a²) sinθ