Anika

Part 1
=== There is three different methods of transmitting television, broadcasting which uses electromagnetic radiation, satellite television which uses satellites, and cable T.V. which transmits the television signals through a pipe. The broadcasting method is the only method that uses electromagnetic radiation.Television uses electromagnetic radiation, by the broadcasting waves that broadcasting stations emit. Those waves are put into the air by the station and they get picked up by your television antenna. The radio waves that are transmitted from the antenna of the broadcasting station carry information that then goes into the antenna of your television antenna. Your antenna turns those signals into an electrical signal. Once the electrical signal is inside our device it turns it into a picture. For television both sound and picture signals are transmitted. Television stations use two methods of transmitting signals, amplitude modulation (AM) and frequency modulation (FM). ===

Amplitude Modulation
Amplitude modulation or AM is a method of transmitting information by changing the amplitude of the wave. The information that will soon become sound, is imbedded in the changes of a wave's amplitude. The frequency of an AM wave stays the same but the amplitude changes in various degrees. Amplitude modulation waves have somewhat long wavelengths, which can bounce back by the Earth's ionosphere. The ionosphere is a layer of the earth's atmosphere that has charged particles, the waves that were reflected then bounce back to the earth's surface. AM waves therefore can travel through long distances. AM waves are measured by a unit called kilohertz (kHz). Here is the process that AM waves go through:

1.At the radio broadcasting station sound is changed into electrical signals in the amplitude of a wave.

2.The electrical signals are then converted into a sequence of changes

3.Your antenna then picks up the waves and changes it back into sound!

This is a diagram of what an Amplitude Modulation wave would look like. The frequency remains constant while the amplitude changes.

Frequency Modulation
Unlike the AM method, frequency modulation (FM) is a method of transmitting signals by altering the frequency of a wave. The amplitude of the wave stays constant, but the frequency changes.Frequency modulation signals move as changes in the frequency of the wave. AM waves have a lower frequency and FM waves have a higher frequency therefore FM waves have more energy than AM waves. Unlike AM waves, FM waves are able to move past the Ionosphere, hence FM waves cannot travel as far as AM waves.FM waves have better sound quality than AM waves, but if you are on a long road trip with an FM radio station then it might be cut off. FM waves are measured by a unit called megahertz (MHz).

The image below represents what a Frequency Modulation wave would look like, keeping the same amplitude but changing the frequency.

Health Affects-
There has been multiple studies on radiation emitted from television, but there is no harmful heath effects. Although there is speculation that t.v. monitors produce x-rays that can be harmful to your health, but that theory has been proven incorrect. There was an experiment based on that speculation, so now we can be sure that we are safe from radiation sickness when we are watching a football game on a Saturday night. Although T.V. monitors do not emit harmful x-rays,there are still precautions set by the government to make sure that the radiation levels are not over the limit. When there is a higher frequency in a wave there is higher energy, therefore when something has really high energy it is probably because of it's frequency levels. There are two terms used for measuring radiation levels, UHF which means Ultra High Frequency and VHF translating into Very High Frequency. When a wave has UHF it has a lot of energy, so it would be more dangerous than waves with VHF frequency levels. To sum it up, televisions are completely safe until proven so. There has been speculation, but even if a television had high radiation levels the health effects would be minimal.

T he electromagnetic spectrum is the sequence of all of the different types of electromagnetic waves. The order is from the electromagnetic wave with the longest wavelength and lowest frequency and energy, to the electromagnetic wave with the shortest wavelength and highest energy and frequency. Basically it is arranged from radio waves, microwaves, infrared, visible, ultraviolet, x-ray, gamma rays, radio waves having the lowest energy and gamma rays with the highest energy. Of all of the electromagnetic waves around us only a small portion of the electromagnetic spectrum contains visible light.

Citations:
"Broadcasting Antenna." //Dream stime//. Web. 14 Apr 2011. .

"Television Antenna." //Granby TV//. Web. 14 Apr 2011. 

"Television with Image." //Electronics Circle//. Web. 14 Apr 2011. 

"Black Arrow." //Eastern Drafting//. Web. 14 Apr 2011. .

"The Electromagnetic Spectrum." //Kellowin//. Web. 14 Apr 2011. .

Pasachoff, Jay. "Student Edition." //Book-specific resources//. Comp. Boston, Massachusetts: Pearson Prentice Hall, 2007. Print