Question

There is an electric field near the earth's surface whose magnitude is about 145 v/m. How much energy is stored per cubic meter in this field?

Answer 1

Given,

Electric Field strength near earth's surface E = 145 V / m

permittivity of free space (electric constant) e_o = 8.854 *10^-12 s^4 A^2 / m^3 kg

To Find,

How much energy is stored per cubic meter in this field?

The solution requires the energy density stored between earth's surface and the source of electric field strength. The formula for charge density is given by:

u_e = 0.5*e_o * E^2

Plug in the values given:

u_e = 0.5*8.854 *10^-12 *145^2

u_e = 9.30777 * 10^-8 J/m^3