AQA Physics 8463 - Waves Lexicon

A complete set of 98 vocabulary retrieval flashcards covering section 4.6 (Waves) of the AQA Physics 8463 specification.

Wave

A disturbance that transfers energy from one place to another without transferring matter overall.

Two Main Types of Wave

Transverse and longitudinal.

Transverse Wave

A wave in which the oscillations are perpendicular to the direction of energy transfer.

Examples of Transverse Waves

Ripples on a water surface or electromagnetic waves.

Longitudinal Wave

A wave in which the oscillations are parallel to the direction of energy transfer.

Example of Longitudinal Wave

Sound waves in air.

Compressions

Regions in a longitudinal wave where particles are closer together.

Rarefactions

Regions in a longitudinal wave where particles are further apart.

Amplitude

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

Wavelength

The distance from one point on a wave to the equivalent point on the adjacent wave.

Frequency

The number of waves passing a point each second.

Unit of Frequency

Hertz, $Hz$.

Period

The time taken for one complete wave cycle.

Unit of Period

Second, $s$.

Equation Linking Period and Frequency

$$T = \frac{1}{f}$$

Wave Speed

The speed at which energy is transferred, or the wave moves, through a medium.

Equation Linking Wave Speed, Frequency and Wavelength

$$v = f\lambda$$

Unit of Wave Speed

Metres per second, $m/s$.

Unit of Wavelength

Metre, $m$.

Effect of Increasing Frequency on Wavelength (Constant Speed)

Wavelength decreases.

Required Practical 8

Frequency, wavelength and speed of waves using suitable apparatus, including a ripple tank and waves in a solid.

Uses of a Ripple Tank

Water waves and their wavelength, frequency and speed.

Wave Speed Calculation Method

Use $v = f\lambda$.

Measuring the Speed of Sound in Air

Measure a known distance and the travel time, or use suitable microphones and timing equipment, then calculate speed.

Sound Wave Changing Media (Physics Only)

Its speed and wavelength can change; its frequency stays the same.

Wave Behavior at Boundaries

It may be reflected, transmitted or absorbed.

Reflection (Physics Only)

A wave changing direction at a boundary and travelling back into the original medium.

Transmission (Physics Only)

A wave passing through a boundary into another material.

Absorption (Physics Only)

Energy from a wave being transferred to the material it enters.

Required Practical 9 (Physics Only)

Reflection of light by different surfaces and refraction of light by different substances.

Refraction

A change in direction of a wave when its speed changes as it enters a different medium.

Cause of Wave Refraction (HT)

Its speed changes when it enters a different medium.

Normal Human Hearing Range (Physics Only HT)

Approximately $20\,Hz$ to $20\,kHz$.

Sensation of Hearing (Physics Only HT)

Sound waves cause the eardrum and other parts of the ear to vibrate.

Ultrasound (Physics Only HT)

Sound with a frequency above the upper limit of human hearing.

Ultrasound Imaging Principle (Physics Only HT)

It is partially reflected at boundaries between different media.

Locating Boundaries with Ultrasound (Physics Only HT)

Measure the time taken for a reflected pulse to return and use the wave speed.

Uses of Ultrasound (Physics Only HT)

Medical imaging and industrial imaging or testing.

Seismic Waves (Physics Only HT)

Waves produced by earthquakes that travel through the Earth.

P-waves (Physics Only HT)

Longitudinal seismic waves that can travel through solids and liquids.

S-waves (Physics Only HT)

Transverse seismic waves that can travel through solids but not liquids.

Seismic Evidence for Earth's Structure (Physics Only HT)

Their speeds, paths and whether they pass through particular regions reveal boundaries and the state of Earth's interior.

Echo Sounding (Physics Only HT)

Using reflected high-frequency sound waves to detect objects underwater or measure water depth.

Nature of Electromagnetic Waves

Transverse waves.

Energy Transfer by Electromagnetic Waves

Energy from a source to an absorber.

Electromagnetic Waves Vacuum Propagation

No medium is needed. They can travel through a vacuum.

Speed of Electromagnetic Waves in Vacuum

Approximately $3.0 \times 10^8\,m/s$.

Electromagnetic Spectrum (Longest to Shortest Wavelength)

Radio, microwave, infrared, visible light, ultraviolet, X-rays, gamma rays.

Electromagnetic Spectrum (Lowest to Highest Frequency)

Radio, microwave, infrared, visible light, ultraviolet, X-rays, gamma rays.

Frequency and Wavelength Relationship in EM Spectrum

It decreases as frequency increases.

Visible Light Spectrum

The part of the electromagnetic spectrum that human eyes can detect.

Visible Light Colour with Longest Wavelength

Red.

Visible Light Colour with Shortest Wavelength

Violet.

EM Wave Behavior at Boundaries (HT)

They may be absorbed, transmitted, reflected or refracted by different amounts depending on wavelength.

Required Practical 10

How infrared radiation absorbed or emitted by a surface depends on the nature of that surface.

Production of Radio Waves (HT)

By oscillations in electrical circuits.

Effect of Absorbed Radio Waves (HT)

An alternating current with the same frequency as the radio wave in an electrical circuit.

Origin of Gamma Rays

Changes in the nucleus of an atom.

Radiation Dose

A measure of the risk of harm from exposure of the body to radiation.

Conversion Between Millisieverts and Sieverts

$$1000\,mSv = 1\,Sv$$

Health Risks of Ultraviolet Radiation

Premature skin ageing and an increased risk of skin cancer.

Hazards of X-rays and Gamma Rays

They are ionising and can cause gene mutations and cancer.

Uses of Radio Waves

Television or radio communications.

Uses of Microwaves

Satellite communications and cooking food.

Uses of Infrared Radiation

Electrical heaters, cooking food and infrared cameras.

Uses of Visible Light

Fibre-optic communications.

Uses of Ultraviolet Radiation

Energy-efficient lamps and sun tanning.

Uses of X-rays and Gamma Rays

Medical imaging and treatments.

Lens Function (Physics Only)

Forms an image by refracting light.

Convex Lens (Physics Only)

A converging lens that brings parallel rays to a focus.

Concave Lens (Physics Only)

A diverging lens that spreads parallel rays apart.

Principal Focus of a Convex Lens (Physics Only)

The point where rays parallel to the principal axis converge after refraction.

Focal Length (Physics Only)

The distance from the lens to its principal focus.

Real Image (Physics Only)

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

Virtual Image (Physics Only)

An image formed where rays appear to come from but do not actually meet, so it cannot be projected onto a screen.

Images Formed by Convex Lenses (Physics Only)

A real or virtual image, depending on object position.

Images Formed by Concave Lenses (Physics Only)

A virtual image.

Magnification Equation (Physics Only)

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

Magnification Unit

No unit. It is a ratio.

Specular Reflection (Physics Only)

Reflection from a smooth surface in a single direction.

Diffuse Reflection (Physics Only)

Scattering of reflected light from a rough surface.

Colour Filters (Physics Only)

They absorb some wavelengths and transmit others.

Colour Determination of Opaque Objects (Physics Only)

The wavelengths it reflects most strongly.

White Objects (Physics Only)

They reflect all visible wavelengths approximately equally.

Black Objects (Physics Only)

They absorb nearly all visible wavelengths.

Transparent Material (Physics Only)

A material that transmits light so objects can be seen clearly through it.

Translucent Material (Physics Only)

A material that transmits light but scatters it, so objects are not seen clearly through it.

Infrared Emission and Absorption (Physics Only)

All objects emit and absorb infrared radiation.

Effect of Temperature on Infrared Emission (Physics Only)

The hotter an object is, the more infrared radiation it emits in a given time.

Perfect Black Body (Physics Only)

An ideal object that absorbs all incident radiation and reflects or transmits none.

Black Body Emission Efficiency (Physics Only)

Good absorbers are also good emitters of radiation.

Body at Constant Temperature (Physics Only HT)

It absorbs radiation at the same rate as it emits radiation.

Temperature Increase Condition (Physics Only HT)

When an object absorbs radiation faster than it emits radiation.

Temperature Decrease Condition (Physics Only HT)

When an object emits radiation faster than it absorbs radiation.

Factors Affecting Earth's Temperature (Physics Only HT)

Rates of radiation absorption and emission, and reflection of radiation back into space.

Waves and Matter Key Concept

Waves transfer energy, but the particles of the medium only oscillate rather than travelling with the wave overall.

Frequency vs. Wave Speed Key Distinction

Frequency is cycles per second; wave speed is how fast the disturbance or energy travels.

Reflection vs. Refraction Key Distinction

Reflection sends a wave back at a boundary; refraction changes its direction because its speed changes in a new medium.