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A point charge Q is placed inside a cavity within a solid isolated conducting sphere. Consider points A, B and C as shown in the figure, where the magnitudes of the electric fields are E_A, E_B and E_C, respectively. The points B and C are at the same distance from the center of the solid sphere. The correct option is :

Asked in Re-NEET 2026 · Conductors and electrostatic shielding

• (1) E_A=0, E_B=E_C
• (2) E_A eq0, E_B=E_C
• (3) E_A=0, E_B>E_C
• (4) E_A eq0, E_B<E_C

Step-by-step solution

Why the other options are wrong

• (1) A is inside the cavity, next to Q, where the field is not zero; the field vanishes only in the metal of the conductor.
• (3) Both parts are wrong: the field at A is not zero, and outside the sphere the field depends only on the distance from its centre.
• (4) Outside, the induced charge +Q spreads uniformly over the outer surface, whatever the position of Q in the cavity, so E_B=E_C.

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