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Question 30739
JEE Physics · Hard

Gravitation: Black Hole Escape MCQ

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Black Hole EscapeHardQuestion 30739

Question

The Schwarzschild radius (event horizon) of a black hole is the radius at which escape velocity equals c. For mass M:
  1. A
    r_s = Gm/c²
  2. B
    r_s = 2GM/c²
    Correct
  3. C
    r_s = GM/c
  4. D
    r_s = c²/2GM

Correct answer

r_s = 2GM/c²

Explanation

Setting v_e = c: c² = 2GM/r_s → r_s = 2GM/c². For Earth, r_s ≈ 9 mm. For the Sun, r_s ≈ 3 km.

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