Question

If potential at the surface of a planet is taken as zero, the potential at infinity will be $(M$ and $R$ are mass and radius of the planet).

• A. Zero
• B. $\infty$
• C. $\frac{GM}{R}$
• D. $-\frac{GM}{R}$

Answer 1

Answer: (C)

$\frac{GM}{R}$

Potential at surface of planet $=\frac{-GM}{R}$. When infinity is taken as reference but here potential will be $+\frac{GM}{R}$ because some positive work must be done to take the particle from infinity to the surface.