Station 1- Structure of Waves
https://www.youtube.com/watch?v=XCu6L4kQF3k
Station 2- Cameras
Film Camera
Digital Camera
Digital Vs. Film Cameras
Pros and Cons
Station 3- Communicating with Waves
Radio waves, microwaves, visible light and infrared can all be used for communication. You
should know some typical examples of these, and associated hazards.
Radio waves
Radio waves are used to transmit television and radio programs. Television uses higher
frequencies than radio.
A radio program receiver does not need to be directly in view of the transmitter to receive
program signals. Diffraction allows low-frequency radio waves to be received behind hills,
although repeater stations are often used to improve the quality of the signals.
The lowest frequency radio waves are also reflected from an electrically charged layer of the
upper atmosphere, called the ionosphere. This means that they can still reach receivers that
are not in the line of sight because of the curvature of the Earth's surface.
Microwaves and radio waves in the atmosphere
Microwaves
Microwave radiation can also be used to transmit signals such as mobile
phone calls. Microwave transmitters and receivers on buildings and
masts communicate with the mobile telephones in their range. Some
people think that mobile phones, which transmit and receive
microwaves, may be a health risk. This is not accepted by everyone, as
the intensity of the microwaves is too low to damage tissues by heating,
and microwaves are not ionizing. Certain microwave radiation
wavelengths pass through the Earth's atmosphere and can be used to
transmit information to and from satellites in orbit. Satellite television signals use microwaves.
Visible light
Visible light is the light we can see. It allows us to communicate with one another through
books, hand signals and video, for example. The use of visible light needs the transmitter and
receiver to be in the line of sight. But it is more secure against eavesdroppers than radio
waves.
Cameras let us record still pictures and movies, and photography is an important use of visible
light. Very bright light can damage our eyes – you should never look directly into the Sun.
Infrared
We cannot see infrared radiation, but we can feel it as heat energy. High intensity infrared is
used in heaters, toasters and grills, and it can cause burns. Infrared sensors can detect heat
from the body. They are used in:
• security lights
• burglar alarms.
Infrared radiation is also used to transmit information from place to place, including:
• remote controls for television sets and DVD players
• data links between computers.
Station 4- Walkie Talkies versus the Cell Phone
Imagine this: it's a gorgeous
winter day and you have been
snowmobiling with your family all
afternoon. However, it's getting
close to being dark and you have
lost track of one of your family
members. You retrace your path,
hoping to find them where you
last remember seeing them.
However, they are not there. You
pull out your cell phone hoping to
call them, but soon realize that
you don't have cell service in the
mountainous terrain. You are
filled with anxiety as you begin to wonder what to do next. If you had walkie talkie you could locate your
missing party in a snap.
Because walkie talkies are based on radio frequencies and not cell towers for service, they are more
reliable than cell phones in certain situations. If you are in a mountainous area, cell phone service may be
obstructed by the trees, whereas the short-range radio frequencies walkie talkies rely on are easier to transmit
and receive.
If you are planning to travel overseas, you may be interested in purchasing walkie talkies for the trip. It
may be more economical for you to spend money these devices rather than using your roaming minutes from
your cell phone.
If you are planning on taking the family on a luxurious cruise ship for a much needed vacation, walkie
talkies could also come in, well, handy. Many cruise lines do not allow the use of cell phones except in certain
areas of the ship, such as staterooms.
Walkie Talkies vs. Cell Phones
Walkie Talkie Cell Phone
Analog Digital
Two way communication Multiple way communication
Uses radio waves Uses cell phone towers
Can communicate only short distances Can make phone calls all over the world
No monthly fee Monthly fee
No roaming or out of country charges Roaming and/or out of country charges
Software applications
Station 5- Comparing Analog to Digital
Comparison Chart
Analog Digital
Signal Analog signal is a continuous Digital signals are discrete time signals
signal which represents generated by digital modulation.
physical measurements.
Waves Denoted by sine waves Denoted by square waves
Representation Uses continuous range of Uses discrete or discontinuous values
values to represent information to represent information
Example Human voice in air, analog Computers, CDs, DVDs, and other
electronic devices. digital electronic devices.
Technology Analog technology records Samples analog waveforms into a
waveforms as they are. limited set of numbers and records
them.
Data transmissions Subjected to deterioration by Can be noise-immune without
noise during transmission and deterioration during transmission and
write/read cycle. write/read cycle.
Response to Noise More likely to get affected Less affected since noise response are
reducing accuracy analog in nature
Flexibility Analog hardware is not Digital hardware is flexible in
flexible. implementation.
Uses Can be used in analog devices Best suited for Computing and digital
only. Best suited for audio and electronics.
video transmission.
Bandwidth Analog signal processing can There is no guarantee that digital signal
be done in real time and processing can be done in real time and
consumes less bandwidth. consumes more bandwidth to carry out
the same information.
Memory Stored in the form of wave Stored in the form of binary bit
signal
Power Analog instrument draws large Digital instrument draws only
power negligible power
Cost Low cost and portable Cost is high and not easily portable
Station 7- Evolution of Cell Phones
Station 9- Music
Analog vs. Digital Music Players
How does a Record Player (Turntable) Work?
The turntable is the circular plate on which the record
sits. The turntable rotates or spins.
The stylus, or needle, is the smallest and perhaps the
most important component of the record player. It is
made from a diamond or other hard material, shaped like
a cone and suspended by a flexible strip of metal. The pointed end is the only piece that
touches the top of the record and it rides around the spiraling grooves of the disk,
picking up the vibrations which are ultimately turned back into sound.
The stylus sits at one end of the tone arm, which is mounted to the side of the turntable
and sits parallel to the record. With the needle or stylus placed in the outermost groove
of the record, the tone arm follows the groove as it spirals inward, traveling across the
record in an arc as the record spins beneath it. As this happens, the vibrations travel
along a flexible metal strip and wires housed in the tone arm to the cartridge in the end
of the tone arm. The cartridge receives the vibrations, which are converted to electrical
signals through a coil in a magnetic field. The electric signals are carried along wires to
the amplifier which enhances the power of the signal. Finally, the signals are converted
back to sounds that come out through the speakers.
How does an MP3 player work?
If MP3s are computer files, it follows that MP3 players must be computers.
All computers, which are machines that process information
(data), have four basic components. They have an input
device (for getting the data in), a memory (for storing
data), a processor (for working on the data), and an output
device (for getting the data back out again).
Switch on your iPod to play your favorite track and it works
just like a computer. The processor chip loads an MP3 file,
reads the ID3 index cards, and displays the artist and track name on the display. Next, it
works its way through the MP3 file reading each frame in turn. It reads the header,
followed by the data, and turns the digital information (the binary ones and zeros) back
into sound frequencies that your ears and your brain decode as music. That's pretty
much all there is to it. But remember this: the real secret of a digital music player is not
the plastic gadget in your hand but the clever technology behind the MP3 files it's playing!
