Question

At some instant and location, the electric field associated with an electromagnetic wave in vacuum has the strength 98.5 V/m. Find the magnetic field strength, the energy density, and the power flow per unit area, all at the same instant and location.

Answer 1

`B = 3.28 * 10^(-7) T`

`u_(density) = 4.3 * 10^(-8) J/m^3`

`Intensity = 12.88 W/m^2`

Step-by-step explanation:

As we know that the electric field strength in vacuum due to electromagnetic waves is given as

`E = 98.5 V/m`

now we know the relation between electric field and magnetic field as

`B = (E)/(c)`

`B = (98.5)/(3* 10^8)`

`B = 3.28 * 10^(-7) T`

For energy density we know that

`u_(density) = (1)/(2)\epsilon_0 E^2`

`u_(density) = (1)/(2)(8.85 * 10^(-12))(98.5)^2`

`u_(density) = 4.3 * 10^(-8) J/m^3`

Power flow per unit area is given as

`Intensity = energy density * speed`

`Intensity = (4.3 * 10^(-8))(3* 10^8)`

`Intensity = 12.88 W/m^2`