The electric potential is 40 V at point A near a uniformly charged sphere. At point B, 2.0 μm farther away from the sphere, the potential has decreased by 0.16 mV. How far is point A from the center of the sphere?

Explanation:

Potential at a point near a charge = Q / 4πε₀ R

where Q is charge given , R is distance of point from the charge .

Q / 4πε₀ R  = 40

Electric field E at A = -dV / dR

= .16 x 10⁻³ / 2 x 10⁻⁶

= .08 x 10³

= 80 N/C

E = Q / 4πε₀ R²

80 =  Q / 4πε₀ R x R

80 = 40 / R

R = 40 / 80

= .5 m .

spectral lines lyman is one set