Waves and the Electromagnetic Spectrum

Vocabulary practice cards defining key wave properties, formulas, longitudinal vs transverse features, and electromagnetic spectrum regions along with their health impacts and uses.

Electromagnetic waves

Transverse waves made of oscillating electric and magnetic fields that transfer energy, can travel through a vacuum, and move at $3.0 \times 10^{8}\,\text{m/s}$ in a vacuum.

Electromagnetic spectrum

The complete range of electromagnetic waves ordered by frequency and wavelength: Radio waves $\rightarrow$ Microwaves $\rightarrow$ Infrared $\rightarrow$ Visible light $\rightarrow$ Ultraviolet $\rightarrow$ X-rays $\rightarrow$ Gamma rays.

Wave speed equation

The equation calculating wave speed by multiplying frequency by wavelength: $v = f \times \lambda$.

Wave speed ($v$)

The speed at which a wave transfers energy, measured in metres per second ($\text{m/s}$); calculated as $\text{frequency} \times \text{wavelength}$.

Frequency ($f$)

The number of wave cycles per second, measured in hertz ($\text{Hz}$); calculated as $\text{wave speed} \div \text{wavelength}$.

Wavelength ($\lambda$)

The distance between corresponding points on consecutive waves, measured in metres ($\text{m}$); calculated as $\text{wave speed} \div \text{frequency}$.

Standard form

A mathematical method writing very large or small numbers as $a \times 10^{n}$, where $1 \le a < 10$.

Transverse wave

A wave in which the oscillations are perpendicular to the direction of energy transfer (e.g., all electromagnetic waves, water surface waves, waves on a string).

Longitudinal wave

A wave in which the oscillations are parallel to the direction of energy transfer (e.g., sound waves, some waves in springs).

Compressions

Regions in a longitudinal wave where the particles are close together.

Rarefactions

Regions in a longitudinal wave where the particles are spread further apart.

Ionising radiation

High-frequency electromagnetic waves (high-frequency ultraviolet, X-rays, and gamma rays) that can damage cells and DNA, increasing the risk of cancer.

Radio waves

Electromagnetic waves with the lowest frequency, longest wavelength, and least energy per photon; used for broadcasting and communication; can cause tissue heating at high intensities.

Microwaves

Electromagnetic waves used for satellite communication and cooking; exposure can cause internal heating of body tissue and burns.

Infrared radiation

Electromagnetic waves used for heaters, thermal imaging, and remote controls; intense exposure can cause heating of skin and tissue or burns.

Visible light

Electromagnetic waves used for vision, lighting, and optical fibres; intense light can damage eyes, particularly the retina.

Ultraviolet (UV) radiation

Electromagnetic waves used for security marking and sterilising; excessive exposure causes sunburn, damages skin cells/eyes, and increases skin cancer risk.

X-rays

Ionising electromagnetic waves used for medical imaging; high or repeated exposure can damage cells and DNA, increasing cancer risk.

Gamma rays

Highly penetrating ionising electromagnetic waves with the highest frequency and energy per photon; used for cancer treatment and sterilising equipment.