Electromagnetic Waves

What are Electromagnetic Waves

Transverse Waves that transfer energy from a source to an absorber

-E.g Microwaves transfer energy from the source(Oven) to the absorber(food)

-E.g Sonal panels- Light waves transfer energy from the source(Sun) to the absorber(Solar panels on aircraft)

On the Red end of the spectrum(Left side)the waves have…

A lower frequency and a longer wavelength

On the violet end of the spectrum(Right side)the waves have….

A higher frequency and a lower wavelength

Which waves on the electromagnetic spectrum can be detected by the human eye

Visible light

Describe pattern of Electromagnetic Spectrum

Raw Meat Is Very Unsanitary except Giraffe

Describe the properties of EM waves

1)All Transverse

2)They all travel through a vacuum

3)All travel at the same speed in a vacuum 3X108 m/s

4)They form a continuous spectrum(Cut off point between one type of wave and another isn’t clear)

Describe colour on EM spectrum

Red

Orange

Yellow

Green

Blue

Violet

What happens when a EM wave is generated or absorbed

Changes take place in atoms or in the nuclei of atom

What happens when we heat atoms

We cause elections to move from one energy level to another higher one

What happens when an electron returns to its original energy level

It generates an Electromagnetic wave(light)

How can an EM wave be generated from a change in nucleus

Gamma rays can be emitted from the nucleus of radioactive atoms so once they’re emitted the nucleus has less energy then at the start

electromagnetic waves can be…

Emitted and absorbed over a wide frequency range from radio waves to gamma rays

How is uV waves, X-rays and gamma rays hazardous to the human body

As they ionise atoms

-Also they have a high frequency so can transfer a lot of energy

How is UV waves dangerous

-Can increase risk of skin cancer

-Can damage surface cells leading to sunburns and skin to age preamp

How are X rays and Gamma rays dangerous

-They’re are ionising radiation so they knock off electrons when they’re absorbed.

-Due to this they can cause mutation of genes and increase the risk of cancer

They damaged caused by radiation depend on…

The type of radiation and the dosage

How are Radio waves produced

-Radio waves can be produced when electrons oscillate in electrical circuits. These radio waves can be absorbed by an electrical circuit in an aerial. So when this happens they now cause electrons in the circuit to oscillate. This creates an alternating current with same frequency as radio waves

What are the uses of radio waves

COMMUNICATION:

-To Transmit radio

-Transmit terrestrial TV signals

Why are radio waves used for these things

As they can travel long distances before being absorbed.

-Also longer wavelength radios can also be spread out between hills

-Radio waves can also reflect off a layer of charged particles in the atmosphere(the ionosphere) allowing us to send radio waves very long distances around the earth

What re the uses of microwaves

-To heat up food as most foods contain water molecules which absorb energy of microwaves. This energy causes the temperature of food to increase

-Used to communicate with satellites in space because microwaves can pass through the Earths atmosphere without being reflected or refracted

What are the uses of Infrared Radiation

-Emitted by electric heaters and all used to cook food in ovens because energy of infrared is easily absorbed by surface of objects e.g infrared from heater is absorbed by objects in room making room warmer

-Alo used in infrared cameras to check builds for heat looses or to locate people

What are the uses of visible light

-Used for communication using fibre optics

-Optical fibres are very thin glass that carry data over long distances as pulses of visible light due to a short wavelength

-Optical fibres are used to carry telephone and cable Tv signals

What are the uses of Ultraviolet

Used for energy efficient lightbulbs- UV light is created inside the bulb and since Uv has a short wavelength it carries more energy than visible light. This energy is absorbed by internal surface of bulb and converted to visible light. This requires less energy than a normal light bulb

-Used in sun tanning for example using a tanning bed which have UV lamps that give people Suntan.

-However there’s increase risk of skin cancer and causes of premature skin ageing.

What are the uses of X-Rays and Gamma Rays

-Both are used for medical imaging:

-X-rays are used to visualise broken bones

-Gamma rays are used to detect cancers

-Both are very penetrative so can easily pass through a body tissue

-Both are used in medical treatments:

-Treatment to cancer because high doses of these kill all living cells, so they can be directed at cancer cells to avoid killing healthy cells

What gives you a X-Ray image

The amount of radiation absorbed from X-Rays by the bones

What can’t X-Rays pass through

Denser material like bones and metal