Topic 5) Light and the electromagnetic spectrum Flashcards
what type of waves are electromagnetic waves?
transverse waves
what do electromagnetic waves transfer?
energy as radiation from the source of the waves to an absorber
where do electromagnetic waves travel?
through a vacuum, such as space
how fast do electromagnetic waves travel in different areas?
at the same through a vacuum or the air
how fast do electromagnetic waves travel?
300,000,000 metres per second (m/s) through a vacuum
what do electromagnetic waves form?
a continuous spectrum of waves
what does a continuous spectrum include?
-waves with a very short wavelength, high frequency and high energy
-waves with a very long wavelength, low frequency and low energy
what are the 7 groups of the electromagnetic spectrum’s?
radio waves
microwaves
infrared
visible light
ultraviolet
x-rays
gamma rays
what is the phrase to help remember the electromagnetic spectrum?
Roman Men Invented Very Unusual X-rays Guns
what are radio waves used for?
communication, such as:
broadcasting television
radio
communications
satellite transmissions
what are the properties of radio waves that make them ideal for transmissions?
-waves can be transmitted easily through air
-don’t cause damage if absorbed by the human body
-can be reflected t change their direction
what produces radio waves?
oscillations in electrical circuits
what happens when radio waves are absorbed by conductors?
they create an alternating current
what are microwaves used for?
cooking food
communications and for satellite communications
why is intense sources of microwaves dangerous?
can causes internal heating of body cells
how do microwaves cause heat?
-high frequency microwaves have frequencies which are easily absorbed by molecules in food
-the internal energy of the molecules increases when they absorb microwaves
what is infrared light used for?
electrical heaters
cookers for cooking food
short-range communications (remote controls)
optical fibres
security systems
thermal imaging cameras
how can infrared effect people?
can cause burns to the skin
what do infrared light do to chemical bonds?
the frequencies are absorbed by chemical bonds
why is infrared light useful for electrical heaters?
the internal energy of the bonds increases when they absorb infrared light, which causes heating
what is visible light used for?
photography
illumination
fibre optic communications
what is ultraviolet light used for?
kill bacteria, disinfecting water
tanning
why is ultraviolet light hazardous?
can cause burns
how are gamma rays produced?
by changes in the nucleus of an atom
why are x-rays ideal for internal imaging?
the high energy waves are transmitted through body tissues with very little absorption
why are x-rays photos used to help identify broken bones?
x-rays are absorbed by dense structures like bones
what are x-rays used for?
internal imaging
internal object imaging (airport security)
what are gamma rays used for?
sterilising food
medical instruments
treating and detecting cancer
what are types of ionising radiation?
ultraviolet waves
x-rays
gamma rays
what do ionising radiation do?
add or remove electrons from molecules, producing electrically charged ions
what are the hazardous effects of ionising radiation on the body?
ultraviolet waves - damage to skin cells and eyes, and increase the risk of kin cancer
x-rays and gamma rays - mutate genes, which can lead to cancer
what are hazards when investigating refraction in rectangular blocks?
ray box gets hot
semi-dark environment
