Module 4 - Section 2 - Types Of Waves Flashcards
What is a transverse wave ?
A transverse wave is a wave where the direction of the oscillations is perpendicular to the direction of energy transfer
What are some examples of transverse waves ?
- Waves on a string
- Ripples on water
- All EM waves
- S-waves
Whats the most common type of longitudinal wave ?
Sound waves
What are mechanical waves ?
Mechanical waves require particles to transfer energy ( they have to travel through a medium )
What is a Longitudinal Wave ?
It is when the direction of oscillation is parallel to the direction of energy transfer
What are the 2 ways of drawing transverse waves ?
They can be shown as graphs of DISPLACEMENT against DISTANCE
OR
They can be shown as graphs of DISPLACEMENT against TIME
Whats the displacement upwards from the centre line given as ?
+ sign
what can be the displacement distance graph used to measure ?
A displacement distance wave profile can be used to show the wavelength of the wave and the amplitude of both types of waves ( transverse and longitudinal )
You measure the wavelength like normal and you measure the amplitude like normal
Whats a wave profile ?
A wave profile is a graph showing the displacement of particles in the wave against the distance along the wave
What can you measure from displacement time wave profile ?
A graph of displacement against time can easily be used to determine the period T and the amplitude of both types of waves - so you measure the period just like you would measure a normal wavelength but instead of measuring the wavelength you are measuring the period as there is time instead of distance on the x axis
Look at the graph with the letter A plotted as a point in the CGP book page 78 ( in blue )
What direction is point A on the wave moving in ?
And then explain how to calculate that
Point A is travelling upwards - all you do is look at the displacement to the left of the the point and you can see that the displacement is much bigger therefore it has to iMovie up to get to that displacement and if the displacement to the left of the point was less then the point A would have the direction of downwards as it would have to move downwards to get to that displacement
What does a sound wave consist of ?
It consists of a series of compressions and rarefactions of the medium its travelling through - that’s why sound can’t go through a vacuum as there’s no particles in a vacuum
Why is it hard to represent longitudinal waves graphically ?
Because they look like transverse waves
How do you plot longitudinal waves on graph ?
Displacement against time graphs - although its hard because they look like transverse waves
What is intensity ?
Intensity is a measure of how much energy a wave is carrying
Intensity is the rate of flow of energy per unit area at right to the direction of travel of the wave - its measured in Wm*-2
When you talk about brightness for light or loudness for sound what are we really referring to ?
When we are referring to how bright a light is what we really mean is how much energy hits you eyes per second
When we are referring to how loud a sound is we are referring to how much energy hits your ears per second
The measure of this is called intensity
Whats the scientific definition of intensity ?
Intensity is the rate of flow of energy per unit area at right angles to the direction of travel of the wave
Whats intensity measured in ?
Intensity is measured in Wm*-2
Whats the equation for Intensity ?
Intensity = Power / area
What is intensity proportional to ?
Intensity is proportional to amplitude squared
And this is because intensity is proportional to the energy carried by the wave - and the energy of a wave depends on the square of the amplitude
What properties do the EM waves have in common ?
- All EM waves travel can travel in a vacuum at a speed of 3.00x10*8 ms and at slower speeds in other media
- They are transverse waves consisting of vibrating electric and magnetic fields - these electric and magnetic fields are at right angles to each other and to the direction of travel
- Like all waves, EM waves can be refracted, reflected and diffracted and can undergo interference. They also obey the v = f x landa equation
- Like all progressive waves, EM waves carry energy
- EM waves are transverse so, like all transverse waves, they can be polarised
Whats the order of the EM spectrum ? And which one has the smallest frequency and which one has the smallest wavelength ?
Radio waves, microwaves, infrared, visible light, ultraviolet, x-rays and gamma rays
Radio waves have the smallest frequency as they have the biggest wavelength and gamma rays have the smallest wavelength and therefore have the most frequency
The longer the wavelength the….
The more obvious the wave characteristics become - long radio waves diffract around hills
What is energy directly proportional to ?
The energy that the wave carries is directly proportional to the frequency of the wave - gamma rays have the highest energy and radio waves have the lowest
The higher the energy that the wave carries the more …
Dangerous the wave becomes as some waves can even cause ionisation
Whats the approximate wavelength (m), how penetrative it is and what are the uses of
Radio waves ?
- Radio waves have a wavelength of 10-1 - 106
- Radio waves are able to pass through matter
- The uses of radio waves are - radio transmissions
What are the uses, penetration and approximate wavelength in m of..
Micro waves ?
The approximate length in m is 10-3 - 10-1
Microwaves mostly pass though matter but cause some heating ]
Microwaves are sued for radar, microwave cooking and Tv transmissions
What are the uses, penetration and approx wavelength in m for …
Infrared radiation
The approx wavelength in m is — 7x10-7 to 10-3
It’s mostly absorbed by matter, causing it to heat up
Infrareds can be used for heat detectors, night vision cameras, remote controls and optical fibres
What is the approx wavelength in m and what’s the uses and penetration ability of visible light ?
The approx wavelength in m for visible light is —> 4x10-7 — 7x10-7
visible light is absorbed by matter which causes some heating
Visible light is used for optical fibres and human sight
Whats the approx wavelength of UV and what’s the penetration and uses of UV ?
The approx wavelength of Uv is —> 10-8 — 4x10-7
UV rays are absorbed by matter and there is slight ionisation
The uses of UV light are - sun beds, security markers that show up under UV light
What is the approx wavelength for X rays and what are the uses and penetration for X-rays ?
The approx wavelength for X-rays is —> 10-13 — 10-8
X-rays mostly pass through matter but they cause ionisation as they pass
The uses of X-rays are —> to see damage form broken bones and teeth, airports security scanners and to kill cancer cells
Whats the approx wavelength for gamma rays and what are the uses and penetration of gamma rays ?
The approx wavelength in m for gamma is —> 10-16 — 10-10
Gamma rays mostly pas though matter but they cause ionisation as they pass
Gamma rays are used for —> the irradiation of food, sterilisation of medical instruments and to kill cancer cells
