Wave Properties

Flashcards for vocabulary related to wave properties.

Amplitude

The measure of the displacement of the wave from its rest position; the greater the amplitude, the greater its energy.

Beats

Two sound waves of different frequency add by constructive and destructive interference producing an alternatively soft and loud sound.

Coherent

Two waves are said to be when they have a constant phase difference between them.

Compression

The region in a longitudinal wave where the particles are closest together.

Crest

The highest point of a wave.

Diffraction

When a wave remains in the same medium but bends around an obstacle or passes through an aperture.

Electromagnetic Wave

Waves that can travel through a vacuum; they do not need a medium; light is an example.

Equilibrium Position

The position the medium would have if there were no wave; it is represented on a graph by a line through the centre of the wave.

Frequency

The number of crests of a wave that move past a given point in a second; the SI unit is the Hertz; it is the inverse of the period.

Interference

When two waves add together to form a resultant wave of lower or greater or the same amplitude.

Longitudinal Wave

A wave where the disturbance moves parallel to the direction of the wave.

Mechanical Wave

A wave that travels through a medium; mechanical waves cannot travel through a vacuum.

Medium

The matter that a wave travels through.

Opaque

Does not allow light to pass through.

Period

The time between wave crests; the SI unit is the second; it is the inverse of the frequency.

Progressive Wave

A wave that moves away from its source.

Propagation

The process by which a wave is transmitted through a medium.

Rarefaction

The region in a longitudinal wave where the particles are furthest apart.

Reflection

Occurs when a wave bounces off a boundary, changing direction but remaining in the same medium.

Refraction

The change in direction and wavelength when a wave moves from one medium to another.

Refractive Index

A number that describes how light travels through a specific medium; different mediums have different refractive indexes; the refractive index of a vacuum is defined to be 1.

Resonance

When the system is driven at its natural frequency, or driving frequency equals natural frequency. It is a large increase of the amplitude of oscillations when a system is driven at its natural frequency, and the transfer of energy is efficient.

Ripple Tank

A shallow glass tank of water used to demonstrate the properties of waves.

Signal Generator

A machine that can produce different patterns of voltage at a range of frequencies and amplitudes.

Standing Wave

A wave that remains in a constant position; also called a stationary wave.

Transducer

Converts a signal from one type of energy into a signal of another type, for example, a sound transducer changes sound energy into electrical energy.

Transparent

A material that allows light through, for example, glass.

Transverse Wave

A wave where the disturbance moves perpendicular to the direction of the wave.

Trough

The lowest part of the wave.

Wave Equation

The relationship between velocity, frequency and wavelength. v = f λ

Wave Velocity

The speed at which the wave travels through a medium; the SI unit is m s-1.

Wavelength

The distance between successive crests or troughs of a wave; the SI unit is the metre.

Free Oscillation

Oscillation of a system with own natural frequence and under no external influence other than impulse that initiated motion

Natural Frequency

The frequency that the object wants to naturally oscillate at

Forced Oscillation

Oscillation of a system with frequency of some external vibrator

Driving frequency

The frequency of the external force applied to a system that causes forced oscillations, which can differ from the system's natural frequency.

What happens when the driving frequency comes close to a systems natural frequency?

The amplitude of oscillations increase

Constructive Interference

 two crests or two troughs arrive at the same point and at the same time, the resultant has twice the amplitude of the original waves

Destructive Interference:

A crest and a trough arrive at the same point and at the same time, and they cancel out

What happens when a wave slows down when it enters a new medium

It will refract towards the normal and the new medium will be more optically dense then the first material

What happens when a wave speeds up when it enters a new medium

THe light will refract away from the normal, meaning the new medium is less optically dense than the first material