P6 - Waves

Comprehensive vocabulary flashcards covering the key properties of mechanical, sound, seismic, and electromagnetic waves, ray optics (reflection, refraction, and lenses), and black body radiation.

What are Waves?

Way energy is transferred through oscillations (fluctuations) or vibrations (repeated movements), without transferring matter

Longitudinal Waves

Particles vibrate parallel to the direction of wave travel and energy transfer

Creates areas of compression and rarefaction.

Transverse Waves

Vibrations are at right angles to the direction of wave travel and energy transfer

Mechanical Waves

Oscillations of particles in a physical medium (solid, liquid, or gas) that require a medium to travel through, such as water or sound waves.

Electromagnetic Waves

Transverse waves consisting of oscillating electrical and magnetic fields that transfer energy as radiation and can travel through a vacuum at $3 \times 10^8\,\text{m/s}$.

Rest Position

The undisturbed position of a wave where the particles are not vibrating.

Crest

The highest point of a wave above its undisturbed rest position.

Trough

The lowest point of a wave below its undisturbed rest position.

Amplitude

The maximum displacement of a wave point from its undisturbed rest position.

Wavelength

The distance covered by a full wave cycle, such as the distance between two consecutive crests or peaks.

Displacement

The distance that a part of a medium has moved from its undisturbed rest position.

Frequency

The number of complete waves passing a specific point each second, measured in hertz ($\text{Hz}$).

Wave Period

The time it takes for two successive crests (one full wavelength) to pass a specific point, calculated as $T = \frac{1}{f}$.

Wave Speed

The speed at which energy is transferred through a medium, given by the wave equation $v = f\lambda$.

Radiation Dose

A measure of the risk of harm resulting from an individual's exposure to ionising radiation, measured in Sieverts ($\text{Sv}$) or millisieverts ($\text{mSv}$), where $1000\,\text{mSv} = 1\,\text{Sv}$.

Law of Reflection

The fundamental principle stating that the angle of incidence equals the angle of reflection ($\text{Angle of incidence} = \text{Angle of reflection}$).

Specular Reflection

Parallel reflection occurring on smooth, flat surfaces (like mirrors), where light incident in a single direction is reflected in a single direction.

Diffuse Reflection

Scattering of light in all directions caused by reflection from a rough surface, resulting in a distorted image or no image.

Refraction

The change in speed and direction of a wave when it crosses a boundary between two transparent materials of different densities.

Normal

An imaginary line drawn at right angles ($90^\circ$) to the boundary or surface where a wave is incident.

Wave Fronts

Lines drawn to connect all adjacent points oscillating in phase (such as peaks or troughs) across a series of waves; the distance between successive wavefronts is equal to one wavelength.

Pitch

A perceptual property of sound that is directly determined by the frequency of the sound wave, with higher frequencies corresponding to higher pitch.

Ultrasound

Sound waves with frequencies greater than $20{,}000\,\text{Hz}$, which is above the upper limit of human hearing.

Echo Sounding

A technique using pulses of high-frequency sound waves to measure water depth and locate underwater objects based on reflection time.

P-waves

Primary seismic waves that are longitudinal, travel faster than S-waves, and can pass through both solids and liquids.

S-waves

Secondary seismic waves that are transverse, travel slower than P-waves, and can only pass through solids.

Convex Lens

A converging lens that is thicker in the middle than at the edges, causing parallel rays of light to refract inwards towards a principal focus.

Concave Lens

A diverging lens that is thinner in the middle than at the edges, causing parallel rays of light to refract outward and diverge from a virtual principal focus.

Principal Focus

The focal point where parallel light rays converge (or appear to diverge from) after passing through a lens.

Focal Length

The distance from the center of a lens to its principal focus.

Real Image

An image formed where rays of light actually meet and focus, which can be projected onto a screen.

Virtual Image

An image formed where light rays only appear to diverge from, which cannot be projected onto a screen.

Magnification

The ratio comparing image size to actual object size, given by $\text{Magnification} = \frac{\text{Image height}}{\text{Object height}}$.

Black Body

An idealized theoretical object that absorbs all incident electromagnetic radiation of all wavelengths, without reflecting or transmitting any, making it the best possible emitter.

Greenhouse Effect

The warming mechanism where greenhouse gases in the atmosphere absorb and re-emit infrared radiation emitted by the Earth's surface, preventing all thermal energy from escaping into space.