A sphere of mass 50gm is suspended by a string in an electric field of intensity $5{\mathrm{NC}}^{-1}$ acting vertically upward. If the tension in the string is 520 milli newton, the charge on the sphere is $\left(g=10{ \mathrm{ms}}^{-2}\right)$

Given data: A sphere of mass 50gm is suspended by a string in an electric field of intensity $5N{C}^{-1}$

Concept used: electric field and electric field line

Detailed solution:

$T+F=0.5 N$ 

 $520\times {10}^{-3}N+\left(5\right)\left(Q\right)=0.5N$ 

 $\Rightarrow 5Q=0.5-0.520$

 $\Rightarrow Q=\frac{-0.02}{5}=-4\times {10}^{-3}\mathrm{C}$