P12 Electromagnetic Spectrum
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are electromagnetic waves transverse or longitudinal?
electromagnetic waves are transverse
what is they property of a transverse wave?
transverse waves oscillate at a perpendicular direction of energy transfer
How fast do electromagnetic waves travel when in a vacuum?
3 x 10^8 m/s
What are the 7 types of waves in the electromagnetic spectrum, starting with the longest?
radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, gamma rays
Which 2 types of electromagnetic waves are considered ionising?
x-rays, gamma rays and some types of ultraviolet radiation
Which 2 types of electromagnetic waves can be used in communication?
radio waves can be used for broadcasting the radio and microwaves can be used for telephones
Which type of electromagnetic wave has lowest and highest frequency?
radio waves has the lowest frequency and gamma rays has the highest frequency
Which type of electromagnetic wave has the lowest and highest energy?
radio waves has the lowest energy and gamma rays has the highest energy
what is an oscilloscope?
a device used to display the wavelength, amplitude and frequency of voltage or current
how do radio waves generate a current?
When radio waves are absorbed, they may create an alternating current with the same frequency as the radio wave itself, so radio waves can themselves induce oscillations in an electrical circuit
what are the 3 uses of radio waves?
television transmission, radio transmission and bluetooth
what is infrared radiation emitted from?
Infrared radiation is emitted from all objects that have thermal energy. The hotter an object is, the more infrared radiation it will emit
3 uses of microwaves
satellite communication, heating food and cooking
3 uses of infrared radiation
infrared cameras to detect monitor temperature, to heat food in a toaster and to heat a room via radiator
what are the key features of visible light?
Our eyes are able to detect those wavelengths of electromagnetic radiation, which allows us to see
What are the 7 colours of visible light, starting with the longest wavelength?
Red, Orange, Yellow, Green, Blue, Indigo and violet
what are the uses of visible light?
cameras and optical fibres
How can ultraviolet radiation be harmful?
It can ionise atoms inside our cells, causing damage. This can lead to sun burn, and in some cases can lead to cancer
what are the4 uses of ultraviolet radiation?
Fluorescent lights, checking for ‘invisible’ markings in things like passports, destroying microorganisms to sterilise water and tanning beds to get a suntan
What is fluorescence?
Fluorescence is the phenomenon of ultraviolet light energy being absorbed and then re-emitted as visible light
What are x-ray machines at the hospital used for?
X-rays are used to view the internal structures of our bodies, to help diagnose illness
What precautions do hospital staff take against the harmful effects of x-rays?
They leave the room when the x-rays are taken and they wear lead vests which stop the x-rays
what are the 3 uses of gamma rays in hospitals?
To sterilise equipment, medical imaging (e.g. radioactive tracers) and to help treat cancer.