TOPIC 2- Waves and the Electromagnetic Spectrum Flashcards
Wavelength
(Lambda)
Peak to peak measurement of length of a wave cycle.
(M)
Amplitude
Displacement from rest position to a crest/trough. (M)
Frequency
The number of complete cycles of the wave passing a certain point per second. (Hertz)
Time period
The time it takes for a wave to carry out one complete oscillation. (S)
1/frequency
Wave speed
Frequency * wavelength
(Lambda)*frequency
Transverse waves
Waves where particles oscillate perpendicular to the direction it’s travelling.
Waves
The transfer of energy and information in the direction that they are travelling.
What happens when waves travel through a medium?
Particles of the medium vibrate and transfer energy/information between each other while particles overall stay in the same place.
Transverse waves
Waves where vibrations are perpendicular to the direction the wave travels. Most waves are.
What type of wave are EM waves?
Transverse
What type of waves are S waves?
Transverse
What types of waves are water ripples?
Transverse
Longitudinal waves
Vibrations are parallel to the direction the wave travels.
Examples of longitudinal waves
Sound waves
P waves
Compressions
High pressure squashes w lots ofparticles
Rarefactions
Low pressure stretches w fewer particles
Wave speed=
Distance/time
Frequency*wavelength
How do you measure the speed of sound?
Attaching a signal generator to a speaker at a specific frequency.
2 microphones and an oscilloscope help to find wavelength of the sound waves generated..
1 start w both microphones next to speaker and slowly move one away until waves on oscilloscope align but moved 1 wavelength apart.
The distance is the wavelength
How do you measure the speed of water ripples
Use signal generator attached to a dipper of a ripple tank, creating waves at a set frequency. Dim lights and turn on strobe light to see wave pattern. Alter strobe light so wave pattern appears to freeze and so stop moving (frequency of waves and strobe light are equal).
Distance between each shadow= one wavelength
How do you find the speed of waves in solids
1 measure and record length of a metal rod
2 attach w elastic bands so hangs w clamps next to microphone.
3tap rod w object and write down peak frequency displayed by computer,
4 repeat *3 to get an average
5 wavelength = twice length of rod
What three things can happen when a wave meets a boundary?
Absorption
Transmission
Reflection
ABSORPTION of waves at boundaries
Wave transfers energy to material’s energy stores, often thermal which leads to heating.
TRANSMISSION at wave boundaries
Wave carries on travelling through new material, often leading to refraction.
Can be used in communications as well as in glasses/camera lenses.
REFLECTION of a wave at a boundary.
Oncoming wave is sent back away from second material.
How echoes are created.