Condition for a uniform spherical mass m of radius r to be a black hole is [ G = gravitational const

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7.Gravitation

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The condition for a uniform spherical mass m of radius r to be a black hole is [ $G$ = gravitational constant and $g$ = acceleration due to gravity]

A

${(2Gm/r)^{1/2}} \le c$

B

${(2Gm/r)^{1/2}} = c$

C

${(2Gm/r)^{1/2}} \ge c$

D

${(gm/r)^{1/2}} \ge c$

Solution

(c) The criterion for a star to be black hole is

$\frac{{GM}}{{{c^2}R}} \ge \frac{1}{2}$ or, $\sqrt {\frac{{2GM}}{R}} \ge c$.

Standard 11

Physics

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