Electromagnetic Spectrum Flashcards
What kind of waves are transverse waves?
transverse
What speed do the waves travel at through a vacuum?
travel at the same speed through a vacuum but they travel at different speeds in different materials
Wave order from long wavelength and low frequency to short wavelength and high frequency?
Radio waves, micro waves, infrared waves, visible light, ultraviolet light, x rays, gamma rays
What do all the waves transfer energy to and from?
example
from a source to an absorber
when you warm yourself by an electric heater, infrared waves transfer energy from the thermal energy store of the heater to your thermal energy store
the higher the frequency the more…
energy it transfers so it is more dangerous for humans
Radio Waves - transmitted, absorbed, reflected, refracted
through the body being absorbed
Microwaves- transmitted, absorbed, reflected, refracted
Can be absorbed, causing heating of cells which can be dangerous
Infrared and Visible Light - transmitted, absorbed, reflected, refracted
Mostly reflected or absorbed by the skin, causing some heating too. IR can cause skin burns if skin gets too hot
Ultraviolet Light - transmitted, absorbed, reflected, refracted
Absorbed by the skin - has a higher frequency so It is more dangerous - ionising radiation and when absorbed it can damage skin cell - skin cancer or eye damage
X rays and Gamma Rays - transmitted, absorbed, reflected, refracted
Ionising radiation- can cause mutations and damage to cells - they have higher frequencies so transfer more energy so can do more damage to deeper tissue
Radio Waves - what are they made up of?
oscillating electric and magnetic fields - alternating currents are made up of oscillating charges - they produce a oscillating electric and magnetic fields
Radio waves - how do you produce them?
using an alternation current in an electrical circuit. The object which charges electrons oscillate to create a transmitter
What are long radio waves used for?
Communication and broad casting for round the world - they bend round curved earth surface
What are short radio waves used for?
communication and broadcasting for far away - as they are reflected by the earths atmosphere
bluetooth
What are microwaves used for?
Cooking, communications and satellite transmissions
What are infrared used more?
cooking, thermal range, optical fibres, tv remotes and security systems
What is visible light used for?
Photography, vision and illumination
What is ultraviolet used for?
Security marking, fluorescent lamps, detecting forged bank notes
What are X rays used for?
Medical x rays, airpot security scanners
What are gamma rays used for?
Sterilising food and medical equipment, the detection of cancer and its treatment
Changes in atoms and nuclei can generate…
be caused by…
radiations over a wide frequency range
absorption of range of radiations
How do microwaves heat up food?
microwaves need to be absorbed by water molecules in food - the microwaves penetrate into the food before being absorbed and transferring energy to water molecules causing the water to heat up- then transfer energy to rest of the molecules
How do infrared cameras work?
The camera detects the IR radiation and turns it into an electrical signal which is displayed on screens as a picture
How do digital cameras work?
They contain image sensors, which detect visible light and generate electrical signal - this is converted to an image that can be stored digitally
