JEE Physics · Hard

Gravitation: Field Inside Solid Sphere MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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Field Inside Solid SphereHardQuestion 30720

Question

Inside a uniform solid sphere of density ρ, radius R, the gravitational field at distance r from centre (r < R) is:
  1. A
    GM/r²
  2. B
    −4πGρr/3
  3. C
    4πGρr/3 (directed inward)
    Correct
  4. D
    Zero

Correct answer

4πGρr/3 (directed inward)

Explanation

Only the mass within radius r contributes: M' = (4/3)πr³ρ. g = GM'/r² = G(4πr³ρ/3)/r² = 4πGρr/3. It increases linearly with r inside the sphere (directed toward centre).