Electromagnetic Waves

The shortest wavelength of all the waves.

Highest frequency of all waves.

Their source can be radioactive substances like uranium.

It is made when there is a change in the nucleus of the radioactive substance.

They can be detected by a Geiger-muller tube.

It is used to get rid of harmful bacteria in food and sterilise surgical equipment. Also used to detect and treat cancer, in radiotherapy.

Can be detected by photographic film.

Dangerous because they kill cells.

It’s source is x-ray tubes.

Can be detected by photographic film.

Used to observe internal structure, people, metal structure, air-port security and archaeology.

Absorbed by bone but transmits or passes through air, skin or soft tissue.

CT Scans are more dangerous than normal X-Rays because they are in a higher dosage.

Produced by accelerating electrons.

Can cause ionisation and can kill or damage our cells. It also alters and damages our DNA cells, which causes mutation.

Used for security markers, fluorescent lamps, washing powder, sunbeds and for disinfecting water, because it kills sewage.

Produced when electrons change energy levels.

You can absorb UV but get visible light- this is called fluorescence.

Can ionise atoms and molecules.

Damages our cells (skin or eye).

Makes you blind or gives you skin cancer in large doses, but small doses are good.

Used to see, for illumination in torches or lightbulbs, for photography and for lasers.

Produced by atoms when electrons change energy levels.

When an atom absorbs light, an electron moves to a higher energy level.

The more levels they jump, the higher the frequency.

Means below red.

Used for heating, grills, toasters, short range communication (remote controls), thermal imaging (searching for people), optical fibres (cable TV), heat treatment and security systems.

Heat is caused by vibrating atoms and molecules.

Given out by all objects that have a temperature.

The hotter the object, the more infra-red it emits.

Can be detected by the skin, thermal cameras and thermometers.

Starts heating from the surface (sun burns).

Dark objects emit and absorb more infra-red than white objects.

Used for cooking, mobile phones, communications and satellite transmissions (radar).

Produced by oscillating electrons in metals.

Strongly absorbed by water.

They make molecules of water vibrate, which leads to heat.

Microwaves heat internally. Start heating objects from the inside and slowly comes out.

Produced by aerials and can also be received by aerials.

Used for TV, Radio, communications, Bluetooth, satellite transmissions (radar).

Produced by oscillating electrons in metals. Causes electrons in metals to oscillate, making an electrical current or voltage.

The oscillations of the electrons and the radio wave have the same frequency.

Atoms, electrons or molecules vibrating leads to heat. Also causes metal to heat up.

ABSORBED- The wave disappears when it enters the material. The energy it is carrying is transferred to the material.

TRANSMITTED- The wave travels through the material and is not absorbed or reflected.

REFLECTED- The wave hits the surface of the material and changes direction without entering the material.

REFRACTED- The wave changes direction because it changes speed when it travels from one material into another.

Radiowaves      Rabbits

Microwaves      Mate

Infra Red           In

Visible Light     Very

Ultra violet       Unusually

X Rays            eXpensive

Gamma Rays   Gardens

As it goes up, the EM spectrum,

1. frequency increases,

2. wavelength decreases,

3. energy increases,

4. danger increases.

· They transfer energy from one place to another.

· They are all transverse waves.

· They can be reflected or refracted.

· They can all travel through a vacuum.

· Wave speed= wave length x frequency.

· They all travel at 300 000 000 m/s in a vacuum.

· The shorter the wavelength, the more danger.

· The higher the frequency, the more dangerous.