TELECOM Communication Using Cables Flashcards
Coded messages are sent from a _____ and picked up by a _______
Transmitter, receiver
Give a method of sending a message using code
Morse code
Give an example of range communication
Telephone
Give the energy changes that occur Ian telephone
Sound to electrical and electrical to sound
The transmitter in a telephone is
The microphone
The receiver in a telephone is
The loudspeaker
What are electrical signals transferred through when using telephone communication?
Wires
What speed to electrical signals travel through wires at?
3x10*8
What happens to the amplitude of louder sounds? Why?
Louder notes have more energy than quiet notes so have a larger amlplitude
What happens to the frequency of sound waves? Why?
High pitch noise produces more waves per second than low pitch so have a higher frequency
What is an optical fibre?
A long thin thread of glass through which light can travel
Can light be reflected?
Yes
State the law of reflection
When light is reflected the angle of incidence is equal to the angle of reflection
How do electrical signals vary with frequency and loudness
The same as sound waves
Give advantages of optical fibres
Smaller, cheaper, lighter, more info transmitted, higher signal quality, less repeaters necessary.
At what speed do signals travel in optical fibres?
2x10*8
Give an advantage of electrical cables
Easier to join together than optical finres
If a a ray of light is reversed what path will it follow?
The same in the opposite direction
Why do optical fibres work?
Total internal reflection
When does total internal reflection occur?
When the incident ray is greater than the critical angle
What is the critical angle for glass?
42
Why is an optical fibre less likely to be interfered with?
It is not electrical so cannot be interrupted by electrical interference
Why are optical fibres cheaper?
Glass is cheaper than copper
How often do electrical wires need boosted?
Every 4km
