Waves Flashcards
How do you calculate period ?
1/frequency
The time it takes for one full oscillation
Measured in seconds
What are transverse waves ?
Waves that have oscillations which are perpendicular to the direction of energy transfer . These include
All electromagnetic waves
Ripples in water
A wave on a string
What is a longitudinal wave ?
Wave which has ocissilations that are parallel to the energy transfer .
What is the wave speed?
Speed at which energy is being transferred .
What is the wave speed equation ?
Frequency x wave length
What is the amplitude of the wave ?
Maximum displacement on the wave from it’s undisturbed position
Measured in m
What is the frequency ?
The number of complete waves per second passing through a certain point
What is the law of reflection ?
Angle of incidence = angle of reflection when measured to the normal
What is the angle of incidence ?
The angle between the incoming wave and the normal wave
What is the angle of reflection ?
The angle between the reflected wave and the normal
What is the normal?
An imaginary line that is the perpendicular to the surface at the point of incidence
What is specular reflection ?
When a wave is reflected in a single direction by a smooth surface .
Like reflections from a mirror
What is diffuse reflection ?
When a wave is reflected by the rough surface . The rays are scattered in different directions
Like a piece of paper
Order of EM WAVES from shortest to longest wave length
Radio waves Shortest wave length Micro waves Infrared waves Visible light Ultra violet rays X rays Longest wave length Gamma rays
Why is there a variety of frequencies between EM waves?
Variation in changes of the nucleus of atoms
What is refraction ?
When a wave crosses a boundary between materials at an angle it will change direction , the wave length will change but the frequency will stay the same
What does refraction depend on?
How much the waves slows down when hitting the material.
Define optical density?
A measure of how quickly light can travel through an object
What are EM waves made out of ?
Oscillating electric and magnetic fields
What are microwaves used for ?
In satellites
For communication to and from satellites microwaves must be used . However they must be able to move through the earths watery atmosphere
Also they can be used for cooking food . In microwave ovens these waves need to be absorbed by water molecules so they use different wave lengths
Uses of infrared rays?
Can be used to monitor temperatures.
Can be used in thermal cameras to pick up hotspots .
Can be used in electrical heaters . They contain a wire which when heated emits infrared radiation . This energy is then transferred into thermal energy stores
Uses of ultraviolet rays ?
Can be used in tanning salons
Can be used in ink . When lighted up the ink will become visible
How is visible light used in fibre optic cables?
Long strings of data can be carried over by pulses of visible light
Thy work because the light rays are reflected of the glass bouncing back and forth
Uses or x rays and gamma rays ?
X rays can be used to detect damage to bones
Gamma radiation can be used as a medical tracer
Radiographers use both rays to kill cancer cells
Dangers of EM waves?
UV waves can cause damage to skin cells. Can increase the risk of cancer
X rays and gamma rays are ionizing radiation which can cause mutations in cells which could lead to cell destruction .
What is black body radiation ?
A black body is an object that absorbs all of the radiation that hits it . No radiation is reflected or transmitted
How does radiation effect the earths temperature ?
Temperature depends on the amount of radiation it reflects , absorbs or emits
How do x rays scan breaks in bones ?
X rays pass easily through materials like flesh but struggle passing through denser materials like bone . So its the amount of radiation that is absorbed that gives you an X ray image
How do colour filters work?
Filter out different wave lengths so that only certain colours are absorbed .
Which of these is an example of a longitudinal wave?
Ripples on the surface of water
Sound waves
X rays
Sound waves