Year 10 Pre-ATAR Physics - Radiation

what is radiation

radiation is energy that travels through space in the form of particles or waves.

examples of radiation

heat, light, sound, x-rays

what are the 2 main types of background radiation

natural and artificial radiation

what are the 2 types of natural radiation

cosmic rays and terrestrial

what is terrestrial radiation

radiaiton emitted by materials present in the crust and atmosphere, e.g radiation emitted by food

what are cosmic rays

high energy particles emitted from sources found in space and the sun. these particles shower the earth but are limited by the atmosphere.

what are cosmic rays mainly

protons (hydrogen nuclei)

what is artificial radiation

radiation produced by human activity through weapon testing, nuclear power and in medicine

what is background radiation

radiation present in low levels everywhere in the environment that is widespread and generally not detrimental to life

what is internal irradiation

radiation that the body has become subject to by eating, drinking or breathing a substance

what is external irradiation

radiation that penetrates the skin from outside the body, like cosmic rays.

what is irradiation

it means "to throw light onto..." so in this case "throw radiation onto..."

what is non-ionozing radiation

radiation that does not carry enouhg energy to break molecular bonds and ionize atoms, by stripping the electrons off them. non ionizing radiation is lower on the electromagnetic spectrum

what is ionizing radiation

radiation with enough energy to break molecular bonds and ionize atoms by stripping them of electrons. ionizing radiaiton is found higher on the electromagnetic spectrum

what are the main 3 types of ionizing radiation

alpha particles, beta particles and gamma rays

what are alpha particles

2 protons and 2 neutrons (positive helium nucleus)

what are beta particles

electrons

what are gamma rays

pure energy (photons) which have no charge or mass and travel long distances

what is an isotope

a variation of an element with the same number of protons and electrons, but a different number of neutrons. it displays the same chemical properties but different physical properties

when does alpha decay occur

atom has too may protons

speed of alpha

slow

ionising of alpha

strong

penetrating of alpha

weak (stopped by paper)

what occurs during beta decay

a neutron transforms into a proton and an electron

speed of beta

medium

ionising of beta

medium

penetrating of beta

medium (stopped by aluminium)

speed of gamma

fast

ionising of gamma

weak

penetration of gamma

strong

does gamma decay occur alone

rarely, it often accompanies alpha or beta

why does gamma decay occur

the nucleus has too much energy

what is transmutation

the conversion of one chemical element into another, through nuclear decay or nuclear reaction

what is a radioisotope

a naturally occuring or artificailly produced isotope that has an unstable nuclei and releases matter or particles upon decay

what is radioactivity

the process of an unstable atom releasing energy or matter. if alpha or beta decay occurs, so does transmutation. radioactivity is random and spontaneous

what is nuclear fission

splitting of an atom nuclei accompanied by release of neutrons

what is nuclear fusion

two lightweight atoms nuclei unite to form a heavier element

what is half life

time taken for a radiactive sample to decay by half

types of UV radiation

UVA, UVB, UVC

what is UVA

weakest UV ray, penetrates deep into skin, not absorbed by ozone much (95% passes through) and it penetrates glass and clouds

what is UVB

shorter ans stronger, penetrates skins 1st layer, causes most sunburn and skin cancer, mostly absorbed by ozone and does not penetrate glass much.

what is UVC

shortest and strongest ray, harmful to skin and eyes, basically all absorbed by ozone, causes damage when intensified

what is the UV index

a scale which meausres suns UV intesnity, it ranges from 0 - 11

what are some uses for radiation

x rays, cancer treatment, smoke alarms, nuclear power, sterilize items, find leaks in pipes

what is the electromagnetic spectrum

a spectrum of the different types of electromagnetic waves/radiation and their frequencies and wavelengths

how do electromagnetic waves differ

different waves have different frequencies, wavelengths and levels of energy. however they all travl at the speed of light and through vacuums

what absorbs electromagnetic radiation

gases in the atmosphere like ozone, water vapour and carbon dioxide

do electromganetic waves ionize?

waves with a higher frequency than visible light are ionzing, but waves with a lower frequency than visible light do not