P12: Electro Magnetic Waves Flashcards
What is the order of waves in the electromagnetic spectrum in order of increaing frequency?
Radio waves Micro waves Infrared radiation Visible light Ulta violet X rays Gamma rays
Can electromagnetic waves travel through a vaccum?
Yes
What is the speed of all the electromagnetic waves?
3 x 10 to the power of 8
How does the wavelength of visible light vary?
400nm-700nm
What do electromagnetic waves transfer?
Hey transfer energy to a source to an absorber
What is the wave speed equation?
Frequency x wavelength
What is light from the sun called?
White light
What does white light contain?
All the colours of the visibile spectrum
How does the heat of an object affect the amount of infrared radiation it emits?
The hotter an object the more infrared infrared radiation it emits
What can infrared radiation do to the body?
- it can be absorbed by the skin
- it can damage, burn or kill the cells because it heats them up
What do optical fibres in communications systems usually do and why?
They usually use infrared radiation instead of visible light
This is because infrared radiation is absorbed less than visible light in glass fibres
What are optical fibres
It is a flexible transparent filter made by drawing glass
What are microwaves used for?
-to carry satellite TV programmes and mobile phone calls.
What are radiowaves used for?
-radio and TV broadcasting, radio communications and mibile phone calls.
What can ionising radiation do?
Makes uncharged atoms become charged
How is ultraviolet waves harmful?
They can harm the skin and eyes
What are gamma rays used for?
- kill bacteria in food
- sterilise surgical equiptment
- kill cancer cells
What are x rays absorbed by?
More bones and teeth than soft tissues
Whyare x-rays harmful because________
X rays are ionising radiation
What are carrier waves?
Waves used to carry any type of signal
What type of wave to carry signals does it depend on?
- how much info is in the signal
- how far the signal has to travel
The shorter the wavelength of a wave
- the more info they carry
- the shorter their range(absorbed by the atmosphere(
-the less they spread out
What are optical fibres
Very thin glass fibres, used to transmit singnals carried by light or infrared radiation
- light rays can’t escape the fibre, when they reach the surface they are reflected back
- optical fibres carry a lot more infomation as light has a shorter wavelength than radio waves
What can ultraviolet waves do to the body?(3 answers)
- can cause blindness
- sun burn
- skin cancer
What do gamma rays and x-rays have in common?(3answers)
- travel straight into and through substances if they are not to dense or thick
- have short wavelengths
- both carry a lot of energy per second
What are the differances between x-rays and gamma rays?(3 ways)
- gamma rays have a shorter wavelength so they can penatrate some substances that x-rays can’t
- gamma raysbare produced by radioactive substances
- x-rays are produced when electrons moving at high speeds are stopped
Benifits of gamma rays(2 things):
- kill cancer cells
- kill harmful bacteria
What is ionisation
X-rays and gamma rays pass througg substances and knock electrons out of an atom
-atoms become charged because they lose electrons
What happens if ionising radiation happens in a living cell?
The cell can be damaged or killed. Low doses of x-rays and gamma rays can cuase gene mutation and canerous growth
X-rays can do what to help us?
- make images of internal body parts
- desteoy tumor near the body surface
Xxrays are absorbed by
Bones and teeth more than soft tissue
Radio waves have the highest______
Wavelength
Gamma rays have the highest______
Frequency
What is the equation for wave speed(m/s)?
Frequency(Hz) X wavelength (m)
What is the speed of all the waves in the electromagnetic spectrum?
3 x 10 to the power of 8
What is white light?
Light from the sun(it has all the colours of the visible spectrum in it)
As the frequency of a wave increases………
Tne energy of a wave increases
The hotter an object is………
The more radiation it emits
How can infrared radiation harm the body?
-absorbed by the skin, it can damage burn or heat the skin cells because the cells are heated
What divices are infrared radiation used in?(4answers)
- optical fibres
- heaters
- remote control
- infrared cameras
What are microwaves used for? (3 answers)
- satellite communications (because they can pass through the atmosphere)
- carry mobile phone signals
- microwave ovens heat food quickly
What are radio waves used for?(2 answers)
- to carry TV,radio and mobile phone signals
- can be used instead of cables to connect a computer (Bluetooth)
List the radiations in order of ionising power?
- alpha radiation-most ionising power
- beta-2nd most ionising power
- gamma-least ionising power
What is Beta radiation stopped by?
A thin sheet of metal
What is gamma radiation stopped by?
Thick lead(gamma radiation has an unlimited range in air)
What is the range of alpha radiation in air?
A few cm
What is the range of beta radiation in air?
1 metre
What can ionising a living cell do?
Damage or kill the cell
