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StarterWrite down 3 things you can remember about the
EM spectrum
Learning Objectives
• Understand the difference between digital and analogue signals
• Explain the uses of the different parts of the EM spectrum
Digital & Analogue Signals
Analogue Signals• An analogue signal is a signal showing a
complete range of frequencies.• Is represented using a diagram of a
continuous wave.• Sound is an example of an analogue signal
Digital Signals• Digital signals can only have 2 values: on or off• Are often represented using the numbers
0 & 1 (0 meaning ‘off’ and 1 meaning ‘on’)• a TV remote uses a
digital signal
Digital signals are like a normal light switch
(on or off)
Analogue signals are like dimmer switches
(they can take any value)
Interference
We sometimes call this noise
Quick Quiz
1. Am I Digital or Analogue?
2. Am I Digital or Analogue?
3. Am I Digital or Analogue?
1, 1,0,0,1,1,1,1,1,1,1,0,1,0,
4. Am I Digital or Analogue?
5. Am I Digital or Analogue?
6. Am I Digital or Analogue?
7. Am I Digital or Analogue?
8. Am I Digital or Analogue?
The EM spectrum(Uses)
Gamma rays
• Have the highest frequency• Have the shortest wavelength
Uses:• Sterilizing surgical equipment• Killing cancer cells
X-rays
• Come after gamma rays in the EM spectrum
Uses:• Viewing internal parts of the body
UV rays
• Are found between X-rays and visible light in the EM spectrum.
Uses:• Sunbeds.....but UV rays can cause skin cancer!!
Visible Light
• Found in the middle of the EM spectrum
Uses:• Photography• Human vision
Infra-red rays
• Found on the opposite side of visible light as UV rays in the EM spectrum.
• Heat radiation
Uses:• Cooking• Remotes• Heat imaging
Microwaves
• Found between IR waves and Radio waves in the EM spectrum.
Uses:• Cooking• Mobile phones
Radio Waves
• Have the longest wavelength• Have the lowest frequency
Uses:• TV and radio signals