Waves (Unfinished) Flashcards
What type of waves are EM waves
Tansverse waves
EM waves characteristics
They travel at the same speed through a air vacume, they travel at the speed of light in a vacume, they travel slower in solids
Wave length of x-rays
10^-10 m
What happens to the wave length and frequency as you go down the EM spectrum
Increasing frequency and decreasing wavelength
Why is there such a large range of frequencies in EM wave spectrum
EM waves are generated by a variety of changes in atoms and their nuclei
Frequency of X-rays
10^17 hz
What is refraction
When waves crosses a boundary between materials at an angle it changes a direction
What effects refraction
How much the wave speeds up or slows down which usually depends on the density of the materials.
What directions do waves bend in refraction
If the wave slows down it will bend towards the normal
If it crosses into a material and speeds up it will bend away from the normal
What happens to the frequency when the wave length changes in refraction
It stays the same
What is the optical density
A measure of how quickly light can travel through, the higher the optical density, the slower light waves travel through it.
What does the angle of incidence always equal
the angle of refelction
How are radio waves made
By oscillating charges and magnetic fields
What does the frequency of the waves produced be eqaul to
The alternating current
What are radio waves used for
Mainly for communication
Long radio waves (1-10km) can be transported half way around the world.
How can short radio waves be transported long distances
Short radio waves (10-100m) can be recieved at long distances from the transmitter as they are reflected from the ionosphere.
Medium wave signals can also be reflected from the ionosphere depending on the atmospheric conditions
What type of video waves are used for TV and radio
Very short wavelengths
What are microwaves used for
Used by satalites for communication
Mircowave ovens
How does microwaves trasmitt from space
It’s signals on a transmitter is transmitted into space where it’s picked up by Saturday receiver dish orbiting and transmits the signal back to a satellite dish on the ground
How are microwaves used in the microwave ovens
Microwaves are absorbed by water molecules in food. The microwave penetrate after a few centimetres into the food little been dissolved and transfers energy to the carrying to the water molecules which then transfers the energy around
How can infrared radiation be used
To increase or monitor temperature
What can infared radiation be used for
Detect infrared radiation and monitor the temperature. The camera to text the IR radiation and turns it into an electrical signal
How can food be cooked by IR radiation
Absorbing IR radiation causes objects to get hotter
How was IR radiation used in electric heaters
Electric heaters contain a long piece of wire that heats up when a current flows through it. The wire that emits a lot of infrared radiation which is absorbed by objects in the air in the room, it is then transferred into thermal energy stores