Electromagnetic radiation behaves as both waves and particles called photons. It propagates at the speed of light in straight lines and is emitted and absorbed by charged particles. Microwaves have a wavelength of around 12.1cm and are used in microwave ovens to heat food by forcing the rotation of water and fat molecules. They can also penetrate forest canopies and be used to measure soil moisture from satellites. MRI uses strong magnetic fields between 0.5-2.0 teslas generated by superconducting magnets cooled with liquid helium to produce detailed images of anatomy.
2. Electromagnetic radiation is a fundamental phenomenon of
electromagnetism, behaving as waves and also as particles called
photons which travel through space carrying radiant energy.
In a vacuum, it propagates at the speed of light, normally in straight
lines. EMR is emitted and absorbed by charged particles. As an
electromagnetic wave, it has both electric and magnetic components,
which continuously oscillate perpendicular to each other and
perpendicular to the direction of energy and wave propagation.
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4. There are different types of electromagnetic waves.
One of them are microwaves. You can even use
microwaves to cook your food. Microwave ovens work by
using microwave about 12.1cm wavelength to force water
and fat molecules in food to rotate. The interaction of
these molecules undergoing forced rotation creates heat,
and the food is cooked
5. Microwaves used by Global Positioning System (GPS) receiver in your
car, can also penetrate the canopy cover of forests to measure the
soil moisture of rain forests. Most communication satellites also use
other microwave bands to send signals to a ground station.
6. Microwaves that penetrate haze, light rain and snow,
clouds, and smoke are beneficial for satellite communication
and studying the Earth from space. The Sea Winds
instrument onboard the Quick Scatterometer (QuikSCAT)
satellite uses radar pulses in the Ku-band of the microwave
spectrum. This scatterometer measures changes in the
energy of the microwave pulses and can determine speed
and direction of wind near the ocean surface.
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8. Radar technology is considered an active remote sensing
system because it actively sends a microwave pulse and
senses the energy reflected back. Doppler Radar,
Scatterometer, and Radar Altimeters are examples of
active remote sensing instruments that use microwave
frequencies
9. Passive remote sensing refers to the sensing of
electromagnetic waves that did not originate from the
satellite or instrument itself. The sensor is merely a
passive observer collecting electromagnetic radiation.
Passive remote sensing instruments onboard satellites have
revolutionized weather forecasting by providing a global
view of weather patterns and surface temperatures.
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12. MRI is a medical imaging technique used in radiology to
investigate the anatomy and physiology of the body in both
health and disease.
The strength of a magnet in an MRI system is rated using a unit
of measure known as a tesla. The magnets in use today in MRI
systems create a magnetic field of 0.5-tesla to 2.0-tesla.
16. Most MRI systems use a superconducting magnet,
which consists of many coils or windings of wire through
which a current is passed, creating a magnetic field of
up to 2.0 tesla. Maintaining such a large magnetic field
requires a good deal of energy, which is accomplished
by superconductivity, or reducing the resistance in the
wires to almost zero.
17. To do this, the wires are continually bathed in liquid helium at
452.4 degrees below zero Fahrenheit. This cold is insulated by a
vacuum.
While superconductive magnets are used the strong magnetic
field formed allows for the highest-quality imaging.