P1.2 Flashcards
Who discovered it
William Herschel, a British astronomer
How was infrared discovered
Herschel split sunlight with a prism and placed thermometers at opsite sides of the spectrum. He found that violet was the coolest and red was the warmest. He then wondered if there was anything hotter and measured beyond the red and got an even warmer reading, discovering infrared
Who discovered ultraviolet
Johann Ritter, he heard about herschels work and wondered if anything was further than violet
How was uv discovered
He used a chemical, silver chloride, which turned black when exposed to light. He knew Violet made it break down faster so he split light and placed it further than Violet and found it broke down even faster, these invisible rays are UV
What is lightspeed
3.0 x 10^8 or 300000Km/s
List types of electromagnetic waves from high to low frequency
Gamma rays X rays UV Visible light IR Microwaves Radio waves
Dangers of UV
Have more energy than visible light so potentially more dangerous. Energy from UV is transferred to our cells which can alter then DNA in the nucleus, causing mutations and can cause cancers
Dangers of Infrared
Skin burns, damaging or destroying cells
What is fluorescence
When a material absorbs invisible light and emits visible light
Why is ionising radiation so dangerous
They can remove electrons from atoms, creating ions. Ions are very reactive so unwanted and dangerous reactions could take place inside of you and cause damage to cells or your DNA
