Electromagnetic Spectrum Flashcards
What is an electromagnetic wave (2)
A transverse wave which transfers energy from a source to an absorber
How fast do EM waves travel through air and a vacuum
At the same speed
What kind of spectrum do they form (2)
A continuous spectrum over a range of frequencies
Give the 7 basic types of electromagnetic waves
Radio waves, Microwaves, Infa red, Visible light, Ultraviolet, X-ray, Gamma rays
How are the EM waves ordered in the table
Increasing frequency and decreasing wavelength
What are EM waves made of
Oscillating electric and magnetic fields
How do radio waves work in a radio
Using an ALTERNATING CURRENT in an electrical circuit. You use a TRANSMITTER (which oscillates charges (electrons) to form radio waves) which ejects the radio waves and which then reach RECEIVER and the RADIO WAVES ARE ABSORBED. The ENERGY TRANSFERRED BY THE WAVES IS TRANSFERRED TO THE ELECTRONS in the material of the receiver. This energy causes the ELECTRONS TO OSCILLATE which generates an ALTERNATING CURRENT. This current has the SAME FREQUENCY AS THE RADIO WAVES WHICH CREATED IT
Give the main uses of each EM wave
Radio Wave - (short-wave- signals reflect off the ionosphere) (long-wave - curves around the world for much longer distances)
Microwaves - communication to and from satellites - microwaves
Infra Red - monitor temperature - infra red cameras to detect human movement in the dark
Visible LIght - optical fibres use visible light to transmit data
Ultraviolet - UV lamps for fake tanning or security pens - only visible under UV light
X-ray - radiographers so see if people have broken bones - kill cancer cells
Gamma rays - medical tracer to se the flow throughout the body - kill cancer cells
How do x-rays work for radiographers
X-rays pas easily through flesh but have trouble passing through denser material (bones). If there is a break in the bone, the gamma rays will be able to pass through and show up as a black crack in the bones.
Are low frequency waves dangerous to the body and what do they do when passing through
Low frequency waves are not dangerous when passing through the body because they transfer little energy, they pass through soft tissue without being absorbed
Are high frequency waves dangerous to the body and what do they do when passing through
High frequency waves like UV, X-Ray and Gamma rays transfer a lot of energy so cause a lot of damage
What do UV rays do to damage the body
UV rays damage surface cells which can result in sun-burn and cause skin to age prematurely. More extreme dangers are skin-cancer and blindness
What do X-rays and gamma rays do to damage the body
X-rays and gamma rays are ionising radiation forms so they can cause gene mutation or cell destruction and cancer
What kind of radiation is X-ray and gamma and what does this mean
Ionising radiation - they can knock electrons off atoms
How do you measure the risk of using radiation dose
Sieverts are used to compare the risk of using the radiation to the risk of not using the radiation
Radiation dose (sieverts) 1000mSv = 1Sv
Sieverts are large so you usually use millisieversts
