Microwaves

external image wavelength_choc1_inline.gifexternal image 675px-EM_Spectrum_Properties_edit.svg-1kdipbf.png

What are they?

A microwave is a kitchen electrical device that passes an electromagnetic wave that is used to cook food. It does so by absorbing energy from the water molecules in the food resulting to heat production. A microwave can also be an electromagnetic radiation with a longer wavelength (between 1 mm and 30 cm) than visible light and can be used to communicate with satellites in the earth's orbit.

Are they dangerous?

Microwaves can be dangerous to humans, that's why microwave ovens are shielded and will not operate unless the door is closed. At 2.45 GHz, the frequency microwave ovens use, the waves are absorbed by water, fats and sugars. When they are absorbed they are converted directly into atomic motion -- heat. This can cause internal damage to many organs. Radar systems usually have saftey measure to prevent people getting too close to the transmitting dish.

Where do they come from?

Microwaves are essentially tremendously high frequency radio waves, which are made by different types of transmitter. For instance, in a mobile phone, they are generated by a transmitter chip and an antenna, while in a microwave oven they are generated by a 'magnetron'.


How do we detect them?

Radar uses microwave radiation to detect the range, speed, and other characteristics of remote objects. Development of radar was accelerated during World War II due to its great military utility. Now radar is widely used for applications such as air traffic control, weather forecasting, navigation of ships, and speed limit enforcement. Microwaves cannot be detected using human senses. Instead, there are devices for this. Microwaves are detected using devices called Geiger Tubes, which are gas-filled tubes that detect when radiation interacts with the gas inside the tubes.

What can they be used for?

microwave ovens

One of the best known uses for microwaves, microwave ovens use a magnetron to produce microwaves. The food inside the microwave oven absorbs these waves, which cause the water molecules to move faster, creating heat. The rate of heating varies according to the moisture content, shape and size of the food, causing uneven absorption and heating in many foods. Microwave ovens generally cook much more quickly than conventional ovens because the molecular friction causes the temperature to rise rapidly.

Radar

Microwaves can penetrate atmospheric conditions such as smoke, haze, fog, pollution and light precipitation, which makes it possible to "see" things with radar that are not otherwise visible. Radar is an acronym for "radio detection and ranging." It works by transmitting bursts of microwaves, then recording the waves as they are reflected by other objects. Radar is used in weather forecasting, satellite imaging and air traffic control and navigation.

Communications

microwaves relay stations and transmission towers form a reliable network for communication by radio, satellite, cell phone and Internet. The ability to transmit through adverse atmospheric conditions is a benefit, but microwaves travel in a straight line and require transmission towers to relay them in different directions. Microwaves offer large amounts of bandwidth for radio transmissions, which alleviates the overcrowding of lower frequencies and allows vast amounts of information to be transmitted wirelessly.

Anything else interesting?

we cannot see them. they quickly penetrate quite deep into materials that contain water, for example most hot food. the energy in these waves make the water molecules vibrate faster,which means the water gets hotter. although they can also heat some metals,there are materials, including many plastics, which they pass right through, without heating at all.Although many plastics ised in bowls or cups will melt and get super-heated in microwave ovens.


X-Rays

What are they?

X-rays are a form of electromagnetic radiation that can be detected by a medium to form an image. It is usually used for medical imaging and diagnosis and can be used for industrial purposes. X-ray radiation pulses are sent through a body and X-ray detectors record these pulses and turn them into images. X-rays are detected by different methods and mediums called image receptors. These mediums may require exposure to the body or no exposure to the body. Well-known image receptors are photographic plates, films, fluoroscopes and rare earth screens

Are they dangerous?

yes an x-ray is dangerous because x-rays are high energy electromagnetic rays. They have a strong ability to ionize air or gas. When X-rays fall on Human body they break up the molecular bonds and produce H and OH free radicals. These free radicals are highly reactive and disturb the proteins which are vital to health. Also it damages the cells and sometimes a damaged cell survives and continues to produce more damaged cells.

Where do they come from?

X-rays are generated by an X-ray tube, a vacuum tube that uses a high voltage to accelerate the electrons released by a hot cathode to a high velocity. They are produced in parcels of energy called photons. X rays are shorter in wavelength than UV rays and longer than gamma rays.

How do we detect them?

Today, X-rays are detected by current. This is the safest method of image detection that results in minimal exposure of the body. An electric current detects the X-ray and sends a signal to a computer. The computer then converts the signal into an image. This form of detection is d the most accurate among image receptors.


In the table below, fill the cells with very brief notes. Use the other pages to gather the information from, and you may want to go outside of this wiki if you really can't find the information here (though I'd be surprised!).



Gamma
X-rays
UV
visible
IR
microwaves
radio
How are they generated?
They are generated by
radioactive
atoms and in nuclear
explosions. They also
come from
stars, black holes and
pulsars.
X-rays are a type of
electromagnetic
radiation that can
penetrate solids
and ionize gas
The main producer of these
rays is the sun however man
made lamps can also
be used to create stronger,
more concentrated rays.
They just appear
Lots of objects produce infared
energy, anything living or warm
will produce a certain amount.
They are emitted from
large stars
and in mobiles
they are made with
a transmitter chip
Radio waves make up part of the
electromagnetic spectrum. These
waves are packets of energy with
differing wavelengths, similar to
visible light waves, X-rays or
Gamma rays, except longer
How are they detected?

We detect gamma rays by

using telescopes,

but they don't look

like normal telescopes.

They observe gamma

rays indirectly,

by monitoring flashes of

visible light.

Gamma rays are a form of

radiation.

Today, X-rays are
detected by current.
This is the safest
method of image
detection
that results in
minimal exposure
of the body. An
electric current detects
the X-ray and sends
a signal to a computer.
The computer then
convertsthe signal into
an image. This form
of detection is the most
accurate among
image receptors.
To detect them you can
simply use a filtratethis is
the cheepest option and
used frequently.As well
as thisyou could use a UV
dectector, theycome in a
range of styles and prices.
As with most things, the
more you pay
the better the quality.
Our eyes see the waves coming.
We cannot see these rays but
things like night-vision goggles
and secial detectorscan allow
us see warm objects emitting
this type of energy.
We use receivers if
they are used in mobile
phones
Antennas designed to detect radio
waves are usually similar in size to the
wavelength they want to detect.
This is why many radio antennas
have to be very long. If the antennas
are not close to the size of the
wavelength they do not usually do
a good job of detecting the waves.
How might they be dangerous?
Gamma are dangerous as
they are radioactive.
But we can use them
to kill cancerous cells and
cure some types of cancer
with them.
They have a strong ability
to ionize air or gas. When
X-rays fall on Human body
they break up the molecula
r bonds andproduce H and OH
free radicals. These free
radicals are highly reactive
and disturb the proteins
which are vital to health.
Also it damages the cells
and sometimes a damaged
cell survives and continues
to produce more
damaged cells.
they can be dangerous as
they damageand kill cells.
When this happens to
us we call it sun burn.
It happenswhen our skin has
seen a lot of sunor due to a
lack of sun cream, and
the skin starts to redden
,it can be sore, but more
often then not calms
down; leaving darker,
or more tanned skin.
But many of the cells
have beenkilled in the
skin, for the minority this
could result in cancer.
not dangerous at all
Infared waves are heat waves,
to much heat will damage or kill
cells causing burns.
Prolonged exposure
can damage the cataract.
radio waves are not dangerous because
they have a low frequency. Large doses
of radio waves are believed to cause cancer,
leukaemia and other disorders. Some people
claim that the very low frequency field from
overhead power cables near their homes has affected their health.
What are the main or most significant uses?
Gamma rays can
abe used to go through
the skin to kill cells,
such as cancerous cells.
This can be used to cure
some types of cancer.
Gamma-induced molecular
changes can also be
used to alter the properties
of semi-precious stones.
Gamma rays can be used to
detect for element of different
planets.
They can be used to scan
a patients body for
irregularities and brakes
in the bones and
dentists use them to loomat
the inside of your
teeth using an X-ray
magnifying
decice which makes them
penitrate through the
bones to reveal any
irregularities
Ultra violet rays can be used
for tanning, in a tanning bed or
by the sun.
We use light to sense
what is around us, it
enables us to see objects and generally survive.
Infrared rays aren't the most
dangerous of the types of radiation.
It is able to burn you but it is more
gentle than even visible light rays.
Infrared is in a sense, heat radiation.
They are used mainly for
heating up food and in
mobile phones
They can be used for AM radio,
FM, radio,TV, mobile phones and
things like the police

Very good work indeed. The material is appropriate and the presentation is very good. The table is sound - but with some odd phrasing (pasted)?
Overall, excellent.
A- merit

<Home page> ALL IMAGES ARE FROM GOOGLE IMAGES.