Poynting Vector

The Poynting Vector is a vector that corresponds to the power generated by an Electromagnetic Wave.

Definition §

Defined in free space, the Poynting vector is given by:

Formula - 1 §

Poynting vector in free space

$$\vec{S}=\frac{1}{{\mu }_0}\vec{E}\times \vec{B}$$

Formula - 2 §

Average Intensity from an Electromagnetic Wave

$$I=\frac{c{\mu }_0}{2}{\vec{E}}_0^2=\frac{c}{2{\mu }_0}{B}_0^2$$

Terms §

• $\vec{S}$ = Poynting vector (in ${\text{W/m}}^2$)
• $\vec{E}$ = Electric Field (in $\text{N/C}$)
  • ${\vec{E}}_0$ = Amplitude of electric field
• $\vec{B}$ = Magnetic Field (in $\text{T}$)
  • ${\vec{B}}_0$ = Amplitude of magnitude field
• $c$ = Speed of light
• ${\mu }_0$ = Permeability of free space
• ${ϵ}_0$ = Permittivity of free space