Waves Flashcards
What is a wave?
Oscillations or vibrations about a rest position.
E.g.
Sound waves cause air particles to vibrate back and forth;
Ripples on the water’s surface cause particles to vibrate up and down
Longitudinal wave
One in which the vibrations of the particles are parallel to the direction in which the energy of the wave travels.
They show areas of compression and rarefaction.
Compression
Regions of high pressure due to particles being close together
Rarefaction
Regions of low pressure due to particles being spread further apart
Examples of longitudinal waves
Sound waves
Ultrasound waves
P type earthquake waves
Transverse wave
One in which the vibrations of the particles are at right angles to the direction in which the energy of the wave travels
Examples of transverse waves
Ripples on the surface of water;
Vibrations in a guitar string;
A Mexican wave in a sports stadium;
S type earthquake waves;
Electromagnetic waves, e.g. light waves, microwaves, radio waves, x-rays
Mechanical waves
Cause oscillations of particles in a solid, liquid or gas and must have a medium to pass through - they cannot pass through a vacuum.
Electromagnetic waves
Cause oscillations in electrical and magnetic fields and can travel through a vacuum
What do all waves transfer?
All waves transfer energy from one place to another, but they do not transfer matter
What unit is frequency measured in?
Hertz (Hz)
Amplitude
The maximum disturbance from its undisturbed position
Wavelength
The distance between a point on one wave and the same point on the next wave
Often measured from peak to peak, or trough to trough
What is the symbol for wavelength
Greek letter lambda, λ
Frequency
The number of waves produced by a source each second.
It is also the number of waves that pass a certain point each second.
What is the unit of frequency?
Hertz (Hz)
Frequency equation
Frequency f = number of waves to pass a point divided by time taken in seconds
Period T
The time taken for one wave to be produced or the time for one complete oscillation or vibration.
It is also the time taken for one whole wave to pass a point.
What is period measured in?
Seconds (s)
What do wavefronts represent?
The vibrating part of a wave.
The distance between two wavefronts is one wavelength, λ
Wave speed equation
Wave speed (v) = frequency (f) x wavelength (λ)
What is wave speed measured in?
Metres per second, m/s
Speed of light and all of the electromagnetic spectrum in a vacuum
3x10⁸ m/s
Speed of sound in air
340 m/s
