Electromagnetic wave

• Electromagnetic waves transport electromagnetic energy.
• The energy carried by electromagnetic waves is often simply called radiant energy or light.
• Electromagnetic radiation can also be described in terms of elementary particles called photons. Photons are energy packets and the quantum of the electromagnetic field.
• Electromagnetic waves represent a form of energy, which is emitted and absorbed by charged particles.
• We can sense electromagnetic waves transferring their energy when sunlight heats our skin.
• The energy that electromagnetic waves transport is linked to their frequency and wavelength. Greater energy corresponds to a higher frequency and shorter wavelength.
• Electromagnetic waves do not require a medium to propagate, hence they can travel through a vacuum.
• Electromagnetic waves are transverse waves, meaning their oscillations are perpendicular to the direction of propagation.

Illustrations of electromagnetic waves

• Electromagnetic waves can be visualized as synchronized oscillations of electric and magnetic fields that propagate at the speed of light in a vacuum.
• Illustrations of electromagnetic waves may highlight:
  • Velocity (v): Measures the rate and direction a wave moves in a specific medium.
    • Velocity represents the speed and direction at which an electromagnetic wave propagates through a medium. It is typically constant for a given medium and is unrelated to wavelength, frequency, or amplitude.
  • Wavelength (λ): The distance over which the shape of a wave repeats. Wavelength is measured in meters or sub-units of metres.
    • wavelength is inversely related to frequency ($f$), according to the equation $v=f\lambda$. This means that as the wavelength increases, the frequency decreases, and vice versa.
  • Frequency (f): Frequency is measured in cycles per second. The unit of frequency is Hertz.
  • Amplitude (A): Amplitude is the maximum magnitude of the wave’s oscillations. It represents the peak value of the wave’s electric and magnetic fields as they oscillate in space.
    • Amplitude is not directly related to velocity, wavelength, or frequency mathematically. However, amplitude does affect the energy carried by the wave. In some contexts, amplitude may be related to the intensity or power of the wave.