Electromagnetic Waves Flashcards
What are the properties of EM waves?
- they are transverse waves (~)
- they travel at the same speed in a vacuum
- the waves transfer energy from the source to the absorber of the wave
- wave energy increases with frequency
- wave energy decreases with wavelength
What are the seven types of EM wave from highest frequency to lowest?
In order of highest frequency to lowest, the seven types are: - gamma - X-ray - ultraviolet (UV) - visible - infrared - microwave - radio The trend in wavelengths is the opposite to frequency, so gamma has the shortest wavelength.
What is the relationship between frequency and wavelength of EM waves?
As wavelength of a wave increases, it’s frequency decreases
Uses and risks of gamma rays
Gamma rays are used for medical imaging and therapy, sterilisation and food preservation. They carry the most energy so can be used to destroy harmful bacteria and tumours.
However, gamma is extremely penetrating and damaging to living tissues and cells.
Uses and risks of X-rays
Low energy X-rays are used for medical and industrial imaging. High energy X-rays are used for treating cancer.
X-rays can also be used for security purposes like detecting weapons at airports.
However, X-rays are highly ionising and can damage body cells even in low doses. Precautions need to be taken to keep exposure to X-rays to a minimum.
Uses and risks of ultraviolet (UV) light
Ultraviolet light is used in medical and forensic photography, disinfection and medical therapy.
Exposure to too much ultraviolet light can cause skin burns, skin cancer and cataract formations in the eye
Uses and risks of infrared waves
Infrared radiation is used in TV controls. Infrared can also be used for security purposes, such as in intruder alarms by detecting body heat.
They also heat food as the frequency is high enough to excite (give energy to) the food particles.
Infrared radiation can cause serious skin burns if emitted from high intensity sources.
