DIFFRACTION

DIFFRACTION

1. WHAT IS ?

   • At the two ends of the opening, waves bend

2. EXAMPLES

   • -WHEN SPREAD INTO A HARBOUR THEY SPREAD OUT MORE IF THE HARBOUR MOUTH IS NARROW
     • -the closely spaced tracks on a CD or DVD act as a diffraction grating to form the familiar rainbow pattern seen when looking at a disc. This principle can be extended to engineer a grating with a structure such that it will produce any diffraction pattern desired
       • -The setting sun appears to be red because of the diffraction of light from dust particles in the atmosphere.

3. EXAMPLES

   • The rainbow pattern found on the hologram of your credit/debit card.
     • The speckle pattern which is observed when laser light falls on an optically rough surface is also a diffraction phenomenon.

4. can produce in

   • sound
     • Sound can diffract through a doorway or around buildings. Lower pitched sounds travel better than high-pitched sounds.
   • Ultrasound
     • Ultrasound is sound with a high frequency. It has a very short wavelength compared with most gaps, so there is very little spreading.
   • Light
     • Light has a very short wavelength compared with most everyday gaps such as windows and doors.
   • Radio waves
     • Long wave radio signals are much less affected by buildings and tunnels than short wave radio signals or VHF radio signals.

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