Working With Waves Flashcards
Understand common features of waves
What is the crest of a wave?
The top of the wave
What is the trough of a wave?
The bottom of the wave
What is a period in waves
The time between two crests of a wave
What is the principal of superposition mean?
When waves from 2 sources arrive at the same place then they add together
What does constructive interference mean for a wave?
If the two waves are the same than the wave gets bigger so it’s louder
What does destructive interference mean for a wave?
If the waves are opposite they are in anti-phase so they cancel each other out making the wave smaller
What is it called when the wave is in phase
Constructive interference
What is it called when the wave is in anti-phase?
Destructive interference
What is the speed of light?
3x10⁸
What is the wave speed of c
3x10⁸
What is the speed of a radio wave?
3x10⁸
What are the two types of waves?
Transverse and longitudinal
What is frequency measured in?
Hertz (Hz)
How do you work out frequency
Wavelength divided by time
Frequency= Wavelength/time (s)
How does amplitude affect light
High amplitude brighter light
How does amplitude affect light
High amplitude brighter light
How does frequency affect light and sound
Sound higher pitch
Different colours for light
What is the compression part of a longitudinal wave
When the waves are close together
What is the rare fraction part of a longitudinal wave
When the waves are furthest apart
How do you work out wave speed and units
Wave speed (ms-¹) = frequency x wavelength
f (Hz) x Lambda (metres)How do you work out waves speed with distance and time
Wave speed equals distance divided by time
Distance/time
How do you work out circumference with radians
2pieRadians
What is a radian
One radian is the angle of an arc that is equal to the radius
What is diffraction
The spreading out of a way when passing for a barrier
What affects the diffraction angle
The diffraction angle increases as the width of the gap decreases
The most diffraction happens when gap = wavelength
What is the interference pattern
Constructive interference and destructive interference makes beams of the light which have darkness in between them
How can you measure wavelength
Using diffraction grating
How does diffraction grating work
Lots of little slits nanometres apart
the light goes through the slits and at certain angles we get constructive interference and destructive interference
How do we measure the wavelength using the angles, how does it work?
A certain angles for you get constructive interference and destructive interference
At these angles for path difference of the rays, from the different slits make the wavelength for a particular colour
What happens when atoms get excited
They in it light as photons
What do elements do and they get excited
Atoms of different elements in different wavelengths/colours of light
if I observe the emission spectrum of a substance we can identify what elements it contains
What does oscillation mean?
Regular repeating motion
What is Resonance?
When 2 things vibrate at the same frequency e.g a string on an instrument.
What does a stationary wave mean?
Stationary waves means no sideways movement. It oscillates between the 2.
What does a node mean on a wave
Zero displacement of the wave
What does an antinode mean on a wave
The maximum displacement of the wave
What does superposition mean?
Superposition refers to when the waves line up the peak on peak, to create a bigger wave (higher amplitude)
What does compression in longitudinal waves mean
when the waves are close together
What does refraction in longitudinal waves mean
when the waves are far apart
What are the first harmonics called?
First 8 are called as octaves
What is the first harmonic known as?
fundamental frequency
What is the wavelength what the fundamental frequency?
½ λ
What are all sound waves?
longitudinal waves
When is resonance useful?
Instruments
Water molecules resonate in microwaves to heat food
TV aerials use resonance to get a stronger signal
When is resonance a problem?
Wind could make buildings such as produce oscillate dangerously
Earthquakes can make buildings oscillate
If machinery resonates it could break e.g washing machines
Why are stationary waves only seen at certain frequencies?
Strings have a series of natural frequencies
Corresponding to a number of half wavelength
A stationary wave is produced only when the frequency of the vibration generator produces waves of those wavelengths
Give one use of fibre optics in medicine?
Endoscopy
Endoscopes
Why is there total internal reflection in an optical fibre?
Fibre optic cable denser than outside/air
Therefore incidence at boundary/reflection
At greater than the critical angle
