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