The Wave Nature of Light

The light from the sun, the microwaves used to cook food, and the radio waves emitted by wi-fi routers are all examples of electromagnetic radiation.

Electromagnetic radiation is the transmission of the energy that comes from the motion of electrically charged particles.

This movement creates perpendicular oscillating electric and magnetic fields propagating through space in the form of waves.

Like all waves, electromagnetic waves are characterized by their amplitude, wavelength, and frequency.

The peak amplitude is the distance from the midline to the peak or trough of a wave. It determines the intensity of the wave. For example, the amplitude of visible light is related to its brightness; the larger the amplitude, the brighter, or more intense, the light.

The wavelength is the distance between identical points on adjacent waves, such as successive peaks or troughs; it is symbolized by the Greek letter lambda. Electromagnetic radiation can be categorized by wavelength, which can range from kilometers to picometers.

For example, the wavelength range of visible light is about 400 to 750 nanometers, which correspond to violet and red light, respectively.

The frequency, which is symbolized by the Greek letter nu, is the number of wave cycles that pass through a reference point in one second and is measured in hertz, or cycles per second. The wavelength is the width of one cycle.

The speed of a wave is the product of its frequency and wavelength. Hence, the frequency of a wave is directly proportional to the speed at which the wave is traveling. However, it is inversely proportional to the wavelength of the wave.

Therefore, waves with long wavelengths, such as radio waves, have low frequencies. These waves are less energetic than waves with high frequencies and short wavelengths, such as gamma rays.