
The charges on the spheres are
qX=σ4πa2qY=−σ4πb2qZ=σ4πc2
It is given that VX=VZ
So,
4πϵ0aqX+4πϵ0bqY+4πϵ0cqZ=4πϵ0cqX+4πϵ0cqY+4πϵ0cqZ⇒aσ4πa2−bσ4πb2+cσ4πc2=cσ4π(a2−b2+c2)⇒c(a−b+c)=(a2−b2+c2)⇒c=a+b=2cm+3cm=5cm
JEE Main 2023 — Physics Electromagnetism
Three concentric spherical metallic shells X,Y and Z of radius a,b and c respectively [a<b<c] have surface charge densities σ,–σ and σ, respectively. The shells X and Z are at same potential. If the radii of X&Y are 2cm and 3cm, respectively. The radius of shell Z is _____cm.
Held on 10 Apr 2023 · Verified 6 Jul 2026.
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