3. • Crest: the highest point of a wave.
• Trough: the lowest point of a wave.
• Rest Line (Equilibrium): the mid-point position of the wave (the
dotted line).
5. • Sound is heard when there are two things
collide with each other
• Sound wave is a longitude wave . Sound
waves are affected by temperature and
atmosphere's pressure
• In water sound waves travel faster due to
particles being more compressed.
• In Air, Sound wave pressure creates rare-
fraction and rare-compression columns of
6. • Sounds of frequency below 20Hz is called
InfraSound can not be heard by human's
ears.
• sound travels the earth so it can be used to
detect nuclear blasts and allows whales to
communicate for 10,000 miles (sound
channel)
7. • Audible Sound are • Computer Sound
sound that can be formats:
perceived by human's
ears . Audible Sounds • MP3 up to 16 kHz.
are sounds in the range
of frequencies 20- • Animal Sound:
20,000
• Sonar-
• Music: music 55 Hz - 50 kHz,192-200kHz
3500 Hz
• Telephone: phone 30- • dolphins: 1-164 kHz
3000 Hz • Bats: 20 - 115 kHz
• Hz • Whale: 30-8000 Hz
8. • Sounds above 20kHz are called Ultra Sound .
Unable to be heard by people, but can be heard
by dogs and dolphins.
9. • A source of light can
have many colors
mixed together & in
different amounts.
When light passed
through Prism it gives
different direction &
individual visible light.
• Candela: is unit of
Intensity.
10. • It is sum of all the individual channels, each
carrying separate info, spread across wide
frequency spectrum.
11. • VLF - Very Low Frequency
• LF - Low Frequency
• MF - medium Frequency
• HF - High Frequency
• VHF - Very High Frequency
• UHF - Ultra High Frequency
• SHF - Super High Frequency
• EHF - Extremely High Frequency
12. Table of ITU Radio Bands
Band No. Symbols Frequency Range
Wavelength
1 VLF 3 to 30 kHz 10 to 100 km
2 LF 30 to 300 kHz 1 to 10 km
3 MF 300 to 3000 kHz 100 to 1000 m
4 HF 3 to 30 MHz 10 to 100 m
5 VHF 30 to 300 MHz 1 to 10 m
6 UHF 300 to 3000 MHz 10 to 100 cm
7 SHF 3 to 30 GHz 1 to 10 cm
8 EHF 30 to 300 GHz 1 to 10 mm
9 Sub-milli 300 to 3000 GHz 0.1 to 1 mm
13.
14.
15. Travel faster when fewer atoms are present:
Vacuum: 300,000 km/s
Air: slightly less than 300,000km/s
Water: 226,000 km/s
Glass: 200,000 km/s
Diamond: 124,000 km/s
16.
17.
18. How do I remember all this?
Try: meaning:
Rabbits Radio
Mate Microwaves
In Infra-Red
Very Visible light
Unusual Ultra-violet
eXpensive X-rays
Gardens Gamma rays
19. The wavelengths of radio waves are long compared to other types of
electromagnetic waves—they range in length from 10,000 kilometers to
less than a meter.
Human-made radio waves are generated when electrons, which are
negatively charged, move back and forth within an antenna. This
movement of charged particles creates a field that radiates out from the
antenna at the speed of light.
The radio portion of the electromagnetic
spectrum is divided into bands. Some
bands are dedicated to
commercial, government, aviation, and
maritime purposes.
Television stations use radio waves to
broadcast their signals through the air, just
as broadcast radio stations do. In fact, the
TV band for channels 2-6 is next to the FM
radio band
20. A. Microwaves range from 1
meter to 1 millimeter and
therefore overlap the Radio
wave band.
B. Microwaves are good for C. Scientists use microwaves to
transmitting information. look for evidence of how the
1. they can penetrate, light, rain universe began.
and snow, clouds, and smoke. 1. In the 1960's scientists
discovered cosmic microwave
background radiation.
2. This radiation, which fills the
entire Universe, is believed to
be a clue to its
beginning, something known
as the Big Bang.
21. Microwaves
Microwave uses include finding planes in the
sky and speeders on the ground
(radar), sending a TV signal from a station to
a broadcasting antenna
(communication), and heating hot dogs
(microwave ovens).
22. A. Infrared light lies between the
visible and microwave portions
of the spectrum.
1. Longer waves are about the size
of a pin head.
a. thermal
2. shorter ones are the size of
cells, or are microscopic.
a. TV remote controls
B. Infrared radiation is great
for studying cloud
structure.
1. Shows more cloud detail
than standard pictures.
C. Satellites have instruments
that measure and record
infrared radiation.
23. Infrared radiation is just below the red
end of the visible spectrum. As the
temperature of an object increases, it
emits more IR radiation and of shorter
wavelenghts, At 500ºC most pbjects
start to emit visible red light as well.
Infrared is used in night vision equipment
when there is insufficient visible light to see. It
can be used to remotely determine the
temperature of objects (if the emissivity is
known). This is termed thermography. Infrared
tracking, also known as infrared homing,
refers to a passive missile guidance system
which uses the emission from a target of
electromagnetic radiation in the infrared part
of the spectrum to track it.
24. Weather satellites
equipped with
Infrared radiation can be scanning radiometers
used as a deliberate heating produce thermal or
source. For example it is infrared images which
used in infrared saunas to can then enable a
heat the occupants, and also trained analyst to
to remove ice from the wings determine cloud
of aircraft (de-icing). heights and types, to
calculate land and
surface water
temperatures, and to
locate ocean surface
IR data transmission is
features
also employed in short-
range communication
among computer
peripherals and personal
digital assistants
25. Richard Of York Gave Battle In Vain. =
Red, Orange, Yellow, Green, Blue, Indigo, and Violet. are the colours
of the visible spectrum. We cannot see Infra-red, but we can feel it
warm our skin when we sit in the sun. Infra-red has a longer
wavelength (less energy) than Red light. We cannot see Ultra-violet
light, but we feel our skin has been burnt by the sun if we were in the
sun too long yesterday. It is the Ultra-violet which is thought to cause
skin cancer. UV light has a shorter wavelength (more energy) than
visible light.
26. 1. Red has the longest
wavelength.
2. Violet has the shortest.
3. When all colors are being
A. The range of reflected, we see white.
electromagnetic waves 4. When all colors are being
that you can detect with absorbed, we see black.
your eyes.
B. Length varies from 390
billionths to 770
billionths of a meter.
C. The color we see is the
one being reflected.
27. A. UV waves are shorter than visible light; therefore, have a higher
frequency.
1. Not visible to the human eye.
B. Have enough energy to enter skin cells and cause cell damage, even
cancer.
1. Earth’s atmosphere (ozone layer) blocks most, but not all UV.
C. Useful in killing bacteria.
28. • Extends from end of the
visible light range to the
X-ray region.
• Has a low power of
penetration; hence, its
direct effects on the
human body are limited to
the surface skin.
• It stimulates the
production of vitamin
D in the skin
29. • Stratospheric Oxygen and Ozone
molecules absorb 97-99% of the
sun's high freguency Ultraviolet light
Without the layer of ozone in the
stratosphere to protect us from
excessive amounts of UV-B radiation,
life as we know it would not exist
30. • THEY CANNOT BE SEEN OR FELT.
X-RAYS MOSTLY PASS THROUGH
SKIN AND SOFT TISSUE, BUT
THEY DO NOT EASILY PASS
THROUGH BONE OR METAL.
• X-RAYS ARE USED TO PRODUCE
PHOTOGRAPHS OF BONES TO
CHECK FOR DAMAGE SUCH AS
FRACTURES. THEY ARE ALSO
USED IN INDUSTRY TO CHECK
METAL COMPONENTS AND
WELDS FOR CRACKS OR OTHER
DAMAGE.
• LOWER DOSES OF X-RAYS CAN
CAUSE CELLS TO BECOME
CANCEROUS
31. • These are the most energetic
wavelengths of light, and they have
the shortest wavelengths. Scientists
know very little about what
produces these wavelengths in
outer space.
• They can pass through many kinds
of materials, including human
tissue. Very dense materials, such
as lead, are commonly used as
shielding to slow or stop gamma
photons.
• They are used for:
• cancer treatment
• measure and control the flow of
liquids in numerous industrial
processes
• sterilize medical equipment in
hospitals
• pasteurize certain foods and
