are waves that are created as a result of vibrations between an electric field and a magnetic field that moves through space at the speed of light.

are similar in that they all move at the speed of light and consist of moving electric and magnetic fields.

All of them exhibit the same characteristic of not requiring any medium to propagate the energy.

parts of em waves

highest point of the wave.

lowest point of the wave.

distance between crest to crest or trough to trough.

the number of waves that pass a fixed point in a given amount of time

are perpendicular to the direction in which the waves move.

transverse waves

em spectrum based on

The behavior of an electromagnetic wave in a substance depends on its

These oscillations may occurvat very low frequency or at an extremely high frequency and the entire range of frequencies is referred to as

are used for communication such as television and radio.

They do not cause damage if absorbed by the human body, and they can be reflected to change their direction.

These properties make them ideal for communications.

are used for cooking food and for satellite communications.

have frequencies which are easily absorbed by molecules in food.

pass easily through the atmosphere, so they can pass between stations on Earth and satellites in orbit.

is used by electrical heaters, cookers for cooking food, and by infrared cameras which detect people in the dark.

has frequencies which are absorbed by some chemical bonds.

useful for electrical heaters and for cooking food.

All objects emit

is useful for detecting people in the dark.

is the light we can see.

It is used in fiber optic communications, where coded pulses of light travel through glass fibres from a source to a receiver.

can kill bacteria that are present in water

this sterilizes the water and makes it safe to drink.

is also good for the skin as it helps to make vitamin D.

are ionizing electromagnetic radiation

obtained by the decay of an atomic nucleus.

are more penetrating, in matter, and can damage living cells to a great extent.

are used in medicine (radiotherapy), industry (sterilization and disinfection) and the nuclear industry.

can be described in terms of a stream of particles contain a particle of energy called photons.

a particle of energy

the process of emitting energy

radiation

such as high energy of protons, neutrons, electrons, atoms, and ions;

either light or sound.

waves

These are composed of unstable atoms that give off their excess energy until it becomes stable.

This happens during the spontaneous change to be more stable.

One way to describe radioactivity of an element is its

which is the time it takes for half of the atoms of a radioactive substance to decay.

can range from less than a millionth of a second to millions of years.

The standard unit of measurement of exposure to ionizing radiation.

This measure the amount of radiation and in 1 Sv is 100x larger than 1 rem.

It is often useful to express the rate at which dose is delivered.

Radiation affects us in two ways:

associated with long term, low level exposure to radiation;

appear in cases of exposure to high levels of radiation and become more severe as the exposure increases.