P1A Topic 2

P1A Topic 2

1. Electromagnetic waves Increases Frequency from left to right meaning the wavelength decreases.

   • Radio waves
     • Broadcast tv and radio.
   • Microwaves
     • Satellite communication
     • Cook food (different wavelength)
   • Infrared
     • Use to monitor temperature (night-vision equipment)
     • Optical fibres transmit data.
     • Used in toaster, remote controls and security system
   • Visible light
     • Too see
   • Ultra violet
     • Used to detect forged banknotes (displays fluorescent markings)
   • X-rays
     • Look inside objects
       • X-rays pass through flesh.
       • X-rays absorbed by bone.
   • Gamma waves
     • Treat cancer
     • Sterilisation of food and surgical instruments.
   • The higher the frequency the more damage it can do. Ex micro = heat body cells, Infra= Skin burns, ultra=skin cancer, Gamma= cell mutation.

2. Herschel

   • Discovered infared (1800)
   • Diffracted white light into the colour spectrum using a prism.
   • Measured each colour using a thermometer.
   • Temperature increased from violet to red
   • Beyond red he found the highest temperature.

3. Ritter

   • Discovered ultraviolet (1801)
   • Diffracted white light into the colour spectrum using a prism.
   • Measured each colour with silver chloride coated strips.
     • Silver chloride when exposed to light turns black from white.
       • Time how long it takes to change.
   • The blue end changed quicker then the red end.
   • Placed one beyond violet quickest change occurred.