Question

a) Find the potential at a point in space located at 0.07m from a charge -50 x10^-6C. Find the potential energy if a charge +4 x10^-6C is located at that point.

Answer 1

$\varphi=\frac{kq_1}r,$

$\varphi=-\frac{9\cdot 10^9\cdot 50\cdot 10^{-6}}{0.07}=-6.4~MV,$

$W=-\varphi q_2,$

$W=6.4\cdot 10^6 \cdot 4\cdot 10^{-6}=25.6~J.$