Modelling With Waves Flashcards
A wave is….
A model for any disturbance that propagates through a medium, transferring energy without the transfer of matter
Amplitude
The maximum displacement of the medium, measured from the equilibrium
Wavelength
Length between any two closest points of the wave that are in the same phase
Period
Time for one wave to complete
Frequency
The number of waves produced in a second
Wave velocity
Distance travelled by a wave in a second
Longitudinal wave examples….
Sound waves, and earthquake and explosion waves, also known as seismic P waves
In a longitudinal wave….
The displacement or the medium is parallel to the propagation of the wave
Transverse waves example
All types of electromagnetic radiation including visible light
Refraction
The change of direction and a wavelength of a wave when it enters a medium where it changes speed
Refraction takes place….
In all waves: sound, water, light, earthquake waves etc
In cold air
Sound waves travel slower
In warm air
Sound waves travel faster
Difference of longitudinal and transverse waves
Transverse waves travel well in solids but not fluids, longitudinal travel through all states of Mayer because their medium particle move parallel to the direction of the wave
What is total internal reflection?
TIR describes light hitting and reflecting off the surface of an object, without transmitting through the surface
When will total internal reflection take place?
It will only take place when: a light Ray is in a more dense medium which is approaching a less dense one. Any angle of incidence for a light Ray which is larger than the critical angle, will create total internal reflection
What is the critical angle?
The critical angle is a certain angle that justifies whether something is refraction or total internal reflection, for glass the critical angle is approx. 42°
TIR in optical fibres
Light goes in at one end and undergoes repeated TIR and emerges at the other end
Crest
The high part of a wave
Troughs
The low parts of a wave
How are sound waves diffracted
Though doorways because the wavelengths of sounds are about the same size as doorways, which is why we can hear people without seeing them
How are light waves diffracted
Light can only be diffracted if it passes though a narrow slit, this shows how light is a wave motion with a small wavelength
Waves can be
Diffracted through a narrow opening
Transverse waves can be
Water or light waves
Longitudinal waves can be
Sound waves
In longitudinal waves
The vibration is along the direction of the waves
The shorter the wavelength
The higher the frequency
In transverse waves
The vibration is at right angles to the direction of the wave
Radio and TV wave diffraction
Affects people living on hills. A radio wave can diffract around the hill, a to wave with a short wavelength doesn’t bend as much
Waves that reflect
Sound and light waves
The angle of incidence equals
The angle of reflection
Refraction is
When a wave changes speed by passing a boundary between 2 substances with different densities. This causes them to change direction
Refraction doesn’t happen
If it crosses the boundary at an angle of 90°, it just continues as a straight line
Reflection acts
Like a mirror
Sound waves are
Longitudinal waves that must pass through a medium
Light and electromagnetic radiation
Travels as transverse waves
The greater the amplitude of a sound wave
The louder the sound
The greater the frequency of a sound wave
The higher the pitch
If sound waves have the same frequency
They will have the same pitch
If sound waves have the same amplitude
They will have the same loudness
The normal range of human hearing
Between 20 Hz to 20,000 Hz (20 kHz)
The direction of vibration in light waves
Is at 90° to the direction that the light travels
Light travels in
Straight lines
Light waves travel though a
Vacuum,cleaning they do not need a substance to travel through rather transparent and translucent substances
The law of reflection
When light reaches a mirror, it reflects off the surface of the mirror
Rays in light reflection
The incident day goes toward the mirror, the reflected Ray goes away from it
Oscillation
A motion that repeats itself in a regular cycle
Medium
Substance or material that carries the wave
Pulse
A single disturbance moving through a medium from one place to another
Propagation
Any ways in which waves travel. Eg for electromagnetic waves, propagation may occur in a vacuum
Longitudinal wave
A wave vibrating in the direction of propagation
Transverse waves
A wave in which the medium vibrates at right angle to the direction of its propagation
What is interference?
When two waves meet while travelling along the same medium
Brightness of light with amplitude:
The higher the amplitude, the brighter the star
Wavelength tells you
The type of light
Amplitude tells you
The intensity of the light
