Poynting vector

Definition

The Poynting vector represents the directional energy flux (the rate of energy transfer per unit area) of an electromagnetic field. It is given by the cross product of the electric field and the magnetic field vectors, denoted as $\mathbf{S} = \mathbf{E} \times \mathbf{H}$.

5 Must Know Facts For Your Next Test

1. The Poynting vector points in the direction that electromagnetic waves propagate.
2. Its magnitude represents the power per unit area carried by an electromagnetic wave.
3. In a vacuum, the Poynting vector is perpendicular to both electric and magnetic fields.
4. The SI unit for the Poynting vector is watts per square meter ($\text{W/m}^2$).
5. It plays a crucial role in understanding energy conservation in electromagnetic systems.

Review Questions

• What does the direction of the Poynting vector indicate?
• How do you calculate the Poynting vector using electric and magnetic fields?
• What are the units of measurement for the Poynting vector?

Related terms

Electromagnetic Wave: A wave composed of oscillating electric and magnetic fields that propagate through space carrying energy.

Electric Field ($\mathbf{E}$): A physical field produced by electrically charged objects; it exerts force on other charges within the field.

Magnetic Field ($\mathbf{H}$): A physical field produced by moving electric charges or magnetized materials; it influences other materials susceptible to magnetism.