Infrared (T3)

Question 1

Describe infrared…

Answer 1

• all heat is infrared radiation and the entire earth is kept warm from the sun’s infrared radiation
• grills and barbecues heat up food using infrared radiation (ovens using convection and hobs use conduction)
• sunburn is caused by infrared from the sun while tanning is from the ultraviolet

Question 2

How do infrared cameras work, and how do some animals see infrared images?

Answer 2

• in infrared cameras or goggles, we are measuring the warmth being radiated by the human body and using it to turn it into a visible image
• some animals can perceive the infrared spectrum and ‘see heat’, for example the pit viper can find prey just from its body heat

Question 3

How was infrared discovered?

Answer 3

• British astronomer William Herschel (1738 - 1822) was viewing the sun when he put coloured filters over his telescope to make his observations safer
• he noticed different colours heated up his telescope by different amounts
• using a prism, he split the visible light and used a thermometer to measure each colour
• he found the temperature rose as he moved from violet to red
• when he measured the the red end of the spectrum, where there was no visible light, he found the temperature to be the highest
• the had discovered infrared

Question 4

List six uses of infrared…

Answer 4

• cooking
• thermal imaging
• short range communications
• optical fibres
• television remote controls
• security systems