P5.2 - The EM Spectrum Flashcards
How are EM waves created?
Vibrating particles create an oscillating electrostatic field, which creates an oscillating magnetic field field.
Repeats while transferring EM energy
What is the amplitude of EM radiation a measure of?
Light intensity
What is the wave speed of all EM waves in a vacuum?
3x10 to the power of 8
How are radio waves produced?
An oscillating potential difference applied across a wire
Those electrons oscillate back and forthat the same frequency, producing electrostatic and magnetic fields (EM field)
Fields travel and cut across an aerial
Electrons inside the aerial oscillate, producing electrical signals
Rank these waves in order of increasing wavelength:
X-Ray
UV
Visible
Gamma
Radio
Microwave
Infrared
Gamma
X-Ray
UV
Visible
Infrared
Microwave
Radio
What can light waves penetrate?
Air and glass
Stopped by solids
What are the uses of light waves?
To see
Cameras
What are the hazards of light waves?
None
What can infrared waves penetrate?
Pass through air and glass
Stopped by solids
What are the uses of infrared waves?
Night vision
Remote controls
What are the hazards of infrared waves?
Absorbed by skin, causing it to heat up
What can microwaves penetrate?
Air and earth’s atmosphere
What are the uses of microwaves?
Cooking food
Mobile phones
Satellite
What are the hazards of microwaves?
Can heat up water, so possible risk to humans
What can radio waves penetrate?
Air and solids
What are the uses of radio waves?
Radio and TV signals
What are the hazards of radio waves?
None
What can UV waves penetrate?
Moderately penetrates Earth’s atmosphere
Can’t penetrate skin
What are the uses of UV waves?
Produces Vitamin D
Detects bodily fluids
Kills bacteria in water
What are the hazards of UV waves?
Somewhat ionising - can damage skin cells, leading to skin cancer
What can X-Ray waves penetrate?
Skin and thin metal
Stopped by bone and dense metals
What are the uses of X-Ray waves?
X-Ray imaging
Treats some cancers
What are the hazards of X-Ray waves?
Lightly ionising
Can damage cells, causing cancer
What can gamma waves penetrate?
Most materials
Stopped by very thick lead
What are the uses of gamma waves?
Treats cancer
Sterilises medical instruments
What are the hazards of gamma waves?
Quite ionising
Can damage cells, causing cancer
