Waves

Vocabulary-based flashcards covering the key concepts of AQA GCSE Physics Topic 6: Waves, including wave properties, sound, ultrasound, the EM spectrum, and lenses.

Wavelength

The distance between the same points on two consecutive waves.

Amplitude

The distance from the equilibrium line to the maximum displacement (crest or trough).

Frequency

The number of waves that pass a single point per second, measured in hertz ($Hz$).

Period

The time taken for a whole wave to completely pass a single point, calculated as $T = \frac{1}{f}$.

Wave Speed Equation

v = f \times \text{\lambda}, where v is the wave speed in $m/s$, f is the frequency in $Hz$, and $\lambda$ is the wavelength in $m$.

Transverse waves

Waves where vibrations are at right angles to the direction of travel, such as light or electromagnetic waves, having peaks and troughs.

Longitudinal waves

Waves where vibrations are in the same direction as the direction of travel, such as sound waves, having compressions and rarefactions.

Reflection

When waves bounce off a flat surface where the angle of incidence is equal to the angle of reflection.

Transmission

The process where waves pass through a transparent material and emerge on the other side.

Absorption

Occurs if the frequency of light matches the energy levels of electrons; the energy is taken up and eventually re-emitted as heat.

Eardrum

A tightly stretched membrane that vibrates at the same frequency as incoming pressure air waves, moving inward during compression and outward during rarefaction.

Cochlea

The part of the inner ear containing fluid and small hairs sensitive to different frequencies that release electrical impulses to the brain.

Human Hearing Range

The range of frequencies humans can typically hear, which is between $20\,Hz$ and $20\,kHz$.

Ultrasound

Sound waves with frequencies higher than the upper limit of human hearing ($20\,kHz$), used for imaging and sonar.

Infrasound

Sound waves with a frequency lower than $20\,Hz$, also known as seismic waves.

P-waves

Longitudinal seismic waves that can pass through both solids and liquids.

S-waves

Transverse seismic waves that move slower than P-waves and can only pass through solids.

Refraction

The bending of a wave as it enters a different medium; it bends towards the normal in denser materials and away from the normal in less dense materials.

Radio Waves

Electromagnetic waves produced by oscillations in electrical circuits that create an alternating current ($AC$) when absorbed.

Convex Lens

A lens wider at the center than the edges that focuses light inwards towards a focal point; used to correct long-sightedness.

Concave Lens

A lens thinner at the center than the edges that spreads light outwards; used to correct short-sightedness.

Magnification Formula

$$\text{magnification} = \frac{\text{image height}}{\text{object height}}$$

Specular Reflection

Reflection from a smooth surface that gives a single, clear reflection.

Diffuse Reflection

Reflection from a rough surface that causes the scattering of light in many directions.

Black Body

An object that absorbs all the radiation it receives (no transmission or reflection) and is also a perfect emitter of all types of radiation.