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Statement-1: A point charge q lies inside a cavity of a conductor, and another point charge Q is outside the conductor. As Q is moved further away from the conductor, the potential difference (V_A - V_B) between two points A and B located inside the cavity stays unchanged. Statement-2: The electric field produced by the charges on the conductor's outer surface together with charges outside the conductor is zero everywhere inside the conducting material. Choose the correct option.

1. Statement-1 is true, Statement-2 is true, and Statement-2 correctly explains Statement-1.
2. Statement-1 is true, Statement-2 is true, but Statement-2 is NOT the correct explanation of Statement-1.
3. Statement-1 is true, Statement-2 is false.
4. Statement-1 is false, Statement-2 is true.

Correct answer: Statement-1 is true, Statement-2 is true, and Statement-2 correctly explains Statement-1.

Solution

The field inside the cavity is determined only by the cavity charge q and the induced charge on the cavity wall, which depend only on q and the geometry - not on the external charge Q. Moving Q changes the charge distribution on the outer surface and the field outside, but inside the conductor (and hence inside the cavity from external sources) that field is zero. Therefore V_A - V_B in the cavity is unchanged, and Statement-2 (the shielding reason) is exactly why Statement-1 is true.

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