Electric field outside charged sphere
$$E = \frac{k\cdot \sigma4\cdot \pi\cdot R^{2}}{r^{2}}$$
E - electric field
k - proportionality coefficient
σ - surface charge density
R - radius
r - distance
k - proportionality coefficient
σ - surface charge density
R - radius
r - distance
Find
It is known that:
= 