Download electromagnetic waves. - khalid

Electromagnetic
wave
Names: Ahmed Ali Saeed Al Sharhan
Khalid alneaimi
Grade 12-3
6.1 Describe electromagnetic waves :
6.1.1 III. Making Electromagnetic Waves:
• Recall: EM waves are made by a vibrating charge.
• This means that a vibrating charge has both an electric.
• field and a magnetic field.
• As the charge vibrates, the electric and magnetic fields change.
• A vibrating electric charge creates an EM wave that travels outward in all
directions
from the charge.
• EM waves are transverse waves because the electric and magnetic fields vibrate
at right angles to the direction the wave travels.
ELECTROMAGNETIC ENERGY
• When you tune your radio, watch TV, send a text message, or pop popcorn in
a microwave oven, you are using electromagnetic energy. You depend on this
energy every hour of every day. Without it, the world you know could not exist.
• Electromagnetic energy travels in waves and spans a broad spectrum from very
long radio waves to very short gamma rays.
6.1.2
• Radiant energy is the energy of electromagnetic waves.
• The quantity of radiant energy may be calculated by Integrating radiant flux (or
power) with respect to time and, like all forms of energy.
• The term is used particularly when radiation is emitted by a source into the
surrounding environment.
• Radiant energy may be visible or invisible to the human eye.
INFRARED WAVES
• A remote control uses light waves just beyond the visible spectrum of light—
infrared light waves—to change channels on your TV.
• A typical television remote control uses infrared energy at a wavelength around
940 nanometers.
INFRARED FILM
• Color Infrared film can record near-infrared energy and can help scientists
study plant diseases where there is a change in coloring and cell structure.
• These two images show the difference between a color infrared photo and a
natural color photo of trees and baby in a park.
6.2 Describe electromagnetic spectrum :
6.2.1 { Radio waves, television waves, and microwaves are all types of
electromagnetic waves. They differ from each other in wavelength. Wavelength is
the distance between one wave crest to the next }.
6.2.2 {The following electromagnetic waves to their frequencies } :
•
•
•
•
•
•
•
Gamma rays: 1019 Hz & Higher
X-rays: 1016 to 1019 Hz
Ultraviolet waves: 1014 to 1016 Hz
Light waves: 7.85 to 4.85 X 1014 Hz
Infra red waves: 1 x 1012 to 4.3 X 1014 Hz
Microwaves: 3 X 108 to 3 x 1011 Hz
Radio waves: 3 X 104 to 3 X 108 Hz
6.2.3
• The last line of numbers in power of 10 gives the wavelength in m. The regions
sometimes do not have a clear cut, because there is considerable overlap. For
example, radio waves and microwaves boundary is very vague, but public
regulation for their application (usage) is strict.
6.3 Describe radio communications :
6.3.1
• Some radio waves carry an audio signal from a radio station to a radio.
• These radio waves carry information that a radio uses to create sound.
• You hear a sound wave when the compressions and rarefactions the sound
wave produces reach your ears.
• A radio wave does not needed wires as it travels through air.
6.3.2
• Radio waves are electromagnetic waves.
• Electromagnetic waves include waves such as X rays, ultraviolet light, visible
light,
infrared rays.
• Radio waves, including AM radio band, FM radio band, and TV, which uses AM
for the picture and FM for the sound.