Visible and UV light

Question 1

What is visible light

Answer 1

• The light that we use to see
• Appears as different colours depending on the wavelength

Question 2

How does the wavelength affect colour of light

Answer 2

• Red has the longest wavelength and violet has the shortes
• ROYGBIV

Question 3

What can visible light be used for

Answer 3

• Used for communication
• We use optical fibres to transmit data

Question 4

How do we use optical fibres

Answer 4

• Optical fibres are made up of thin glass or palstic
• We send pulses of light. This light reflects everytime it hits the surface of the optical fibre
• Light emerges at the other end where it can be interpreted as information / data

Question 5

What are the characteristics of optical fibres

Answer 5

• Allow us to transmit data very quickly over large distances
• We can only use materials that completely reflect light (none is absorbed)
• Must be specular reflection, not diffused

Question 6

Optical fibres vs copper wires

Answer 6

• Optical fibres allow much more information to be transmitted
• Optical fibres have a lower risk for the information to be distorted

Question 7

What are the characteristics of ultraviolet light

Answer 7

• Shorter wavelength than visible light
• It is emitted by the sun and gives us sunburn / sun tan
• It is used in sun beds to give an artifical tan

Question 8

What is flourescence

Answer 8

• A property that some chemicals have which allows them to absorb UV radiation and re-emit the energy as visible light

Question 9

How do flourscence bulbs work

Answer 9

• Generates and emits UV radiation
• UV radiation is absorbed by a layer of phosphorus covering the inside of the bulb
• This energy is re-emitted as visible light
• Very energy efficient

Question 10

What is UV light used for (water)

Answer 10

• Used to kill microorganisms and sterilise water