Wave Properties and the Electromagnetic Spectrum

A set of vocabulary flashcards covering wave definitions, mathematical formulas, refraction rules, and the components and hazards of the electromagnetic spectrum.

Waves

Phenomena that transfer energy and information without transferring matter.

Transverse waves

Waves where the oscillations are perpendicular ($90^{\circ}$) to the direction of energy transfer, such as water, light, and all EM waves.

Longitudinal waves

Waves where the oscillations are parallel to the direction of energy transfer, such as sound waves and ultrasound.

Compressions

Bunched up, high pressure regions found in longitudinal waves.

Rarefactions

Stretched out, low pressure regions found in longitudinal waves.

Wavelength ($\lambda$)

The distance from one point on a wave to the exact same point on the next wave (e.g., crest to crest), measured in metres ($m$).

Amplitude

The maximum displacement of a point on a wave away from its undisturbed position, measured from the middle line to the top peak.

Frequency ($f$)

The number of complete waves passing a point per second, measured in Hertz ($Hz$).

Period ($T$)

The time taken for one complete wave to pass, calculated using the formula $T = \frac{1}{f}$.

Wave Speed ($v$)

Calculated by the formula $v = f \times \lambda$, where speed is in metres per second ($m/s$), frequency is in Hertz ($Hz$), and wavelength is in metres ($m$).

Refraction

The changing of direction of a wave when it crosses a boundary between two different materials at an angle due to a change in speed.

Speed of light

The speed at which all electromagnetic waves travel through a vacuum, which is $3 \times 10^8\,m/s$.

Radio Waves

EM waves with the lowest energy and longest wavelength, used for television and radio communications.

Microwaves

EM waves used for satellite communications and cooking food.

Infrared (IR)

EM waves used for electrical heaters, cooking food, and thermal imaging cameras.

Visible Light

The only part of the EM spectrum human eyes can detect, used for fibre optic communications.

Ultraviolet (UV)

EM waves used for energy-efficient lamps and sunbeds.

X-rays

EM waves used for medical imaging to view internal broken bones.

Gamma Rays

EM waves with the highest energy and shortest wavelength, used for sterilising medical equipment and treating cancer.

Ionising radiation

High-energy EM waves (UV, X-rays, and Gamma rays) that can knock electrons out of atoms, leading to gene mutation or cell damage.

Sieverts ($Sv$)

The unit of measurement for radiation dose, which quantifies the risk of harm to body tissues.