Two metallic spheres of radii 1 cm and 3 cm are given charges of -1 x 10⁻² C and 5 x 10⁻² C, respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is:

Options

(a) 2 x 10⁻² C
(b) 3 x 10⁻² C
(c) 4 x 10⁻² C
(d) 1 x 10⁻² C

Correct Answer:

3 x 10⁻² C

Explanation:

At equilibrium potential of both sphere becomes same if charge of sphere one x where Q= 4 x 10 10⁻² C
v₁ = v₂ kx / 1cm = k(Q – x) / 3 cm
3x = Q – x 4x = Q
x = Q/4 = 4 x 10⁻² / 4 C = 1 x 10⁻²
Q’ = Q – x = 3 x 10⁻² C