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Saturday, 16 March 2013

Uses of Polaroid

Uses of Polaroid

  1. Polaroids are used in the laboratory to produce and analyse plane polarised light.
  2. Polaroids are widely used as polarising sun glasses.
  3. They are used to eliminate the head light glare in motor cars.
  4. They are used to improve colour contrasts in old oil paintings.
  5. polaroid films are used to produce three-dimensonal moving pictures.
  6. They are used as glass windows in trains and aeroplanes to control the intensity of light. In aeroplane one polaroid is fixed outside the window while the other is fitted inside which can be rotated. The intensity of light can be adjusted by rotating the inner polaroid.
  7. Aerial pictures may be taken from slightly different angles and when viewed through polaroids give a better perception of depth.
  8. In calculators and watches, letters and numbers are formed by liquid crystal display(LCD) through polarisation of light.
  9. Polarisation is also used to study size and shape of molecules.  

Friday, 8 March 2013

Types of Crystals

Types of Crystals

Crystals like calcite, quartz, ice and tourmaline having only one optic axis are called uniaxial crystals.

Crystals like mica, topaz, selenite and aragonite having two optic axes are called biaxial crystals

Monday, 4 March 2013

Polarisation

Polarisation

The phenomena of reflection, refraction, interference, diffraction are common to both transverse waves and longitudinal waves. But the transverse nature of light waves is demonstrated only by the phenomenon of polarisation.