# Shared Flashcard Set

## Details

Waves
Basic wave terms
13
Physics
Not Applicable
09/14/2005

Term
 What does a wave do?
Definition
 A wave transports energy from one place to another
Term
 What are mechanical waves?
Definition
 Mechanical waves use particles to transfer energy (neighbouring particles bump into each other and set their neighbours moving). Eg. sound waves use air particles so it cannot travel through a vacuum (a vacuum is empty space with no particles in it at all!). Sound travels faster through solids than liquids than gases because the particles are more closely packed.
Term
 What are electromagnetic waves?
Definition
 Electromagnetic waves don't use particle vibration to transfer their energy (in fact particles interrupt their progress through a material) and can therefore travel through a vacuum. e.g. light
Term
 What is the unit of frequency?
Definition
 Frequency is measured in hertz (Hz)
Term
 What is the wave equation?
Definition
 wavespeed = frequency x wavelength
Term
 Define a longitudinal wave.
Definition
 The vibrations in a longitudinal wave are parallel to the direction in which the energy is travelling. Eg. sound.[image]
Term
 Define a transverse wave.
Definition
 The vibrations in a transverse wave are perpendicular (at right angles) to the direction in which the energy is travelling. Eg. light.[image]
Term
 Define wavelength.
Definition
 Wavelength (lamda a Greek letter 'l') is the shortest distance between two particles that are oscillating in phase. (Distance between two crests on a displacement/distance graph). It is measured in metres (m) [image]
Term
 What is the period of a wave?
Definition
 Period (T) is the time taken for one complete oscillation of a particle in the wave. (Distance between two crests on a displacement/time graph). It is measured in seconds (s).[image]
Term
 What is amplitude?
Definition
 Amplitude (A) is the maximum displacement from the mean position. (To the top of a crest or bottom of a trough from the middle line in either graph).[image]
Term
 What is frequency?
Definition
 Frequency (f) is the number of oscillations per second. It cannot be read directly off a graph. You need to find (T) from the displacement/time graph and then find its reciprocal (f =1/T)
Term
 What are analogue signals?
Definition
 Analogue signals contain all the information as a continuously varying wave.[image]
Term
 What are digital signals?
Definition
 Digital signals are a series of pulses - either high or low - on or off - sometimes expressed as binary code 1s and 0s.[image]
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