Two concentric thin metallic shells A and B have radii R and 2R respectively. Shell A carries a charge +Q and shell B carries a charge -2Q . What is the net electric potential at a distance of r = 1.5R from the common centre?

Step-by-step solution

The point at r = 1.5R lies outside shell A and inside shell B. The electric potential due to shell A at this point is: V_A = 1 4 ₀ +Q 1.5R = 1 4 ₀ 2Q 3R The electric potential due to shell B at any point inside it is equal to its surface potential. Thus, the potential due to shell B at r = 1.5R is: V_B = 1 4 ₀ -2Q 2R = - 1 4 ₀ Q R By the principle of superposition, the net electric potential is: V_ net = V_A + V_B = 1 4 ₀ ( 2Q 3R - Q R ) = - 1 4 ₀ Q 3R The incorrect options result from sign errors, assuming the fie