Waves Flashcards
What is a wave?
A wave is the movement of energy
What is a transverse wave?
When the displacement (vector version of distance) is at a right angle of the direction of the wave.
What is a longitudinal wave?
When the displacement is parallel to the direction of the wave.
What are compressions?
Areas of high pressure
What are compressions?
Areas of high pressure
What are refractions?
Areas of low pressure
What is amplitude?
How high the wave is
What is a wavelength? What is it measured in?
the distance between two corresponding points on the wave. It is measured in meters.
What is frequency and what is it measured in?
Frequency is how many waves pass by every second, it is measured in hertz (Hz)
What is a wavefront?
The crest (the top bit) of the wave viewed from above.
How fast does an electromagnetic (EM) wave travel through a vacuum? How does it vary with different types of EM waves?
300,000,000m/s and it does not vary with any waves, they all travel at the same speed through a vacuum
What are all the different types of electromagnetic waves IN ORDER?
Gamma rays X-Rays Ultraviolet Visible light Infrared Microwaves Radio/TV
What does light do when entering a more dense medium?
The light slows down and bends towards the normal
What happens to light when it enters a less dense medium?
The light speeds up and bends away form the normal.
Radio waves can also be used as carrier waves in order to send a signal, what is the process of this?
Radio waves are produced in a transmitter using oscillations.
The wave is then transmitted through the air.
The radio then turns the radio wave back into an electrical signal. The oscillating wave induces an oscillating electrical signal.
Give two sources of radiation.
The sun, which sends a light wave.
Gamma radiation where the wave comes from inside the change in the nucleus.
People that work with radiation a lot have to wear something that measures the radiation dosage, what is this called? What is radiation measured in
A dosimeter, which measures radiation in Sieverts (Sv), 1000 millisieverts is equal to 1Sv
How can gamma radiation, x-rays and ultraviolet be dangerous?
Gamma radiation causes the mutation of cells and can lead to cancer.
X-rays can cause cell mutation and cancer (this is why doctors are not in the room when an x-ray is happening because constant exposure means higher risk of cell mutation)
Ultraviolet causes premature aging of the skin and skin cancer (which is why sunscreen is so important)
Why can radio waves travel further distances after being refracted of the atmosphere?
This is because they suffer little absorption. This is why they are used to communicate with satellites.
What is an example of Infrared being used in everyday life? Explain what it does.
A remote control send a signal which contains a set of digital codes which carry different instructions to the device its being sent to.
What is a use of gamma rays and what are the dangers?
Treating cancer (by killing the mutated cells) but it can cause mutation of the healthy cells
What is a use of x rays and what are the dangers?
medical uses but it can lead to cell mutation
What is a use of ultraviolet and what are the dangers?
sun tanning but can lead to skin cancer.
What is a use of visible light and what are the dangers?
Seeing things, fibre optic cables, there are no dangers (unless you look at the sun)
What is a use of infrared and what are the dangers?
remote controls and heat transfer
What is a use of microwaves and what are the dangers?
satellites and phones, heating food. There are very few dangers
What is a use of TV/radio waves and what are the dangers?
Communication, there are very few dangers
How do lenses use the idea of refraction?
When light enters a more dense medium it slows down.
What is the reason we see certain colours?
We see certain colours because all the other colours have been absorbed by that object, white reflects all seven colours.
What is a converging lense?
A lense that is thickest at the centre
What is a diverging lense?
A lense that is thinnest at the centre.
How does a converging lense refract light?
The light is refracted inwards and once it goes through the lense it meets at a focused point (a singular point). A real image or virtual image is formed, a real image can be seen on a screen whereas a virtual image cannot.
How does a diverging lense refract light?
The rays of light are refracted outwards and a virtual image is always formed (in other words, the image does not actually exist)
What happens when light hits glass, wood, a mirror and a rough surface?
Glass- transmission
Wood- absorption
Mirror - specular reflection (transmitted in a different direction)
A rough surface- Diffuse reflection
What can filters be used for?
Filters can be used to block out all other colours by absorbing certain colours and letting others pass through.
What is the difference between an transparent and a translucent object?
A transparent object is one that lets all light through, a translucent object is one that allows light through but blocks or absorbs some of it.
