Final answer:
The Poynting vector is the directional energy flux of an electromagnetic wave and is calculated as the cross product of the electric and magnetic fields of the wave, representing the intensity or power per unit area of the wave.
Step-by-step explanation:
The Poynting vector in physics represents the directional energy flux (the rate of energy transfer) of an electromagnetic wave traveling through a medium. It is defined as the cross product of the electric field (E) and the magnetic field (B). The magnitude of the Poynting vector is equal to the intensity of the wave, which is the power per unit area perpendicular to the direction in which the wave is traveling.
For plane electromagnetic waves, the Poynting vector points in the direction of energy propagation, which is also the direction of wave advancement. If a wave with known electric and magnetic fields is considered, its Poynting vector can be calculated using the equation S = E × B, where S is the Poynting vector. This physical quantity is crucial for understanding how electromagnetic energy is distributed in space and how it interacts with materials, which is pertinent to fields like wireless communication and optical technologies.