Malus law & polarization Experiment

Item Code: SK045

When a light beam passes through a polarizer filter, it gets linearly polarized. When this linearly polarized light passes through analyzer, its intensity depends on the angular position of the analyzer. The maximum light intensity is transmitted when the optical axis of polarizer and analyzer coincide. The intensity of transmitted beam depends on the angular position between the optical axis of the polarizer and analyzer (q) and is defined by Malus law as
I=I0 cos2θ
where I0 is the intensity of incident light.

Further the intensity of light depends on the distance between the source and the detector and is defined by the inverse square law.




  • Pin hole with silicon photo detector.
  • He-Ne laser with built-in power supply.
  • Heavy, rigid and stable Optical bench (made of Al extrusion)
  • Saddle can hold rod from 8 to 15mm.
  • Height and level adjustment screws (made of SS)
  • Analyser/Polayser with 0 ± 90° graduation.

Learning Objectives/experiments

  • To measure the light intensity of plane polarized light as a function of the analyzer position.
  • To verify Malus law.
  • To verify inverse square law.
  • Laser : He-Ne Laser (632mm), Power 2 mW, Beam spot 2.5mm, current 4mA ~ 6mA, Dimension 300 x 62 x 82mm, Weight 1.5 kg (approx.)
  • Optical bench : Al exclusion, L=1/2 mtr., Triangular shape with end stop, 4 point levelling (steel screw)
  • Transversal slider : 25 – 0 – 25mm, LC 0.01mm,
  • Polarizer : Angle (0 + 90°), LC 1°, Aperture 21mm, Frame 130mm, Rod 10 mm
  • Fixed slider : Al Extrusion, Base width 50mm, H 115mm
  • Photo detector : Silicon photocell terminals 4mm safety socket, aperture 1 mm, Rod10mm dia.
  • Connecting lead : Type Banana plug, Length 100cm
  • 1 He-Ne laser
  • 1 Optical bench, 1/2 meter
  • 3 Fixed saddle slider
  • 1 Digital multimeter (801 auto)
  • 2 Polarizer / Analyzer
  • 1Transverse saddle slider
  • 1 Photo detector
  • 1 Flexible plug lead red
  • 1 Flexible plug lead black
  • Polarization
  • Malus law
  • Polarizer, Analyser
  • Circularly and elliptically polarized light.
  • Plane of polarization.