Calculating the Frequency of EM Waves

Lower frequency = Longer wavelengths.

The frequency of a wave is a measurement of the number of waves passing a given point in a given time!

The frequency of a given electromagnetic wave can be calculated by dividing the speed of light in a vacuum (300,000,000 m/s) by its wavelength measured in metres.

The frequency of incident light is unchanged as it travels from air into glass so its colour remains the same.

The frequency of incident light is unchanged as it travels from air into water and undergoes refraction.

The frequency of electromagnetic radiation (light) refers to the number of wave-cycles of an electromagnetic wave that pass a given point in a given amount of time.

• Frequency is measured in Hertz (Hz) and signifies the number of wave-cycles per second. Sub-units of Hertz enable measurements involving a higher count of wave-cycles within a single second.
• The frequency of electromagnetic radiation spans a broad range, from radio waves with low frequencies to gamma rays with high frequencies.
• The wavelength and frequency of light are closely linked. Specifically, as the wavelength becomes shorter, the frequency increases correspondingly.
• It is important not to confuse the frequency of a wave with the speed at which the wave travels or the distance it covers.
• The energy carried by a light wave intensifies as its oscillations increase in number and its wavelength shortens.

The hertz (symbol: Hz) is a unit used to measure the frequency of electromagnetic waves. It represents the number of wave-cycles per second.

• One hertz is defined as one cycle per second.
• Hertz measure the number of oscillations of the perpendicular electric and magnetic fields in electromagnetic radiation per second.
• Frequency conversions:

• 1 Hertz (Hz) = 1 cycle per second
• 1 Kilohertz (kHz) = 1,000 (thousand) cycles per second
• 1 Megahertz (MHz) = 1,000,000 (million) cycles per second
• 1 Gigahertz (GHz) = 1,000,000,000 (billion) cycles per second
• 1 Terahertz (THz) = 1,000,000,000,000 (trillion )cycles per second

A wave is a disturbance that travels through a medium or space, transporting energy from one point to another. Waves can travel through a medium, like waves rippling across a lake, or through space, like the electromagnetic waves that carry sunlight to Earth.

• Electromagnetic waves are generally invisible to the human eye, the exception is the visible spectrum, with wavelengths between approximately 400 and 700 nanometres.
• Beyond this range, whether the wavelengths are longer (as in radio and microwaves) or shorter (as in ultraviolet, X-rays, and gamma rays), our eyes cannot detect them.
• Although we cannot see most electromagnetic waves, we can perceive some in other ways. For instance, infrared waves are felt as heat, and electric current (which produces electromagnetic waves) can cause a buzzing sensation in a wire or cause electrocution.

A wave-cycle is the complete up-and-down motion of a wave, from one crest (peak) to the next crest, or from one trough (dip) to the next trough. Visualize a wave cycle as a series of points plotted along the path of a wave from one crest to the subsequent crest.

• All electromagnetic waves have common characteristics like crests, troughs,, wavelength, frequency, amplitude, and propagation direction.
• As a wave vibrates, a wave-cycle can be seen as a sequence of individual vibrations, measured from one peak to the next, one trough to the next, or from the start of one wave cycle to the start of the next.
• A wave-cycle refers to the path from one point on a wave during a single oscillation to the same point on completion of that oscillation.
• Wavelength meanwhile, is a measurement of the same phenomenon but in a straight line along the axis of the wave.

Wavelength is the distance from any point on a wave to the corresponding point on the next wave. This measurement is taken along the middle line of the wave.

• While wavelength can be measured from any point on a wave, it is often simplest to measure from the peak of one wave to the peak of the next, or from the bottom of one trough to the bottom of the next, ensuring the measurement covers a whole wave cycle.
• The wavelength of an electromagnetic wave is usually given in metres.
• The wavelength of visible light is typically measured in nanometres, with 1,000,000,000 nanometres making up a metre.
• Each type of electromagnetic radiation – such as radio waves, visible light, and gamma waves – corresponds to a specific range of wavelengths on the electromagnetic spectrum.