6.3 Wave theory of light
(18 Periods)
 Huygen's construction
as applied to reflection and refraction.
Speed of light
in air.
Interference of
light and its apllications.
- conditions for interference.
- Young's double slit interference; derivation of
l = aDx
D
- thin films.
Diffraction
- demonstration of diffraction using water
wave in a ripple tank.
single slit diffraction of light.
- plane transmission grating and application
of formula dsinq = nl
in the determination of wavelength.
Polarisation
- as a phenomenon associated with transverse
waves.
- producing polarised light by reflection,
double refraction,
selective absorption and scattering.
- application of polarisation.
Assessment objectives
By the end of this topic, the student should be
able to:
- Define a wave front.
- Distinguish between circular and plane wave fronts.
- Describe Huygen's construction.
- Apply Huygen's construction to reflection and refraction
of
light
- Describe a terrestrial method of measuring the speed
of light.
- Explain the terms coherent sources of light,
path difference and
optical as applied to light.
- Explain interference by "division of wave fronts".
- Describe Young's double slit experiments.
- Explain destructive and constructive interference.
Derive and use the equation l = aDx
- Describe an experiment for measuring l
using the double slit
arrangement.
- State factors which determine the appearence of fringes.
- Explain interference by "division of amplitude".
- Explain interference of light waves in thin films.
- Perform and describe an experiment to demostrate
diffraction of water
waves in a ripple tank.
- Explain diffraction of waves.
- Describe plane transmission grating.
- Use the expression dsinq = nl
- Describe an experiment to determine l using
diffraction grating.
- Explain the terms polarisation, polarised light and
polaroid.
- Describe polarisation of light by: reflection, double
refraction, selective
absorption and scattering methods.
- State and use Brewster's Law.
- Explain applications of polarisation e.g. in sacce
harimetry, photoelasticity,
- reducing light intensity and 3-D pictures (holography)
End of S5 Term 3.
Estimated Time: 10 weeks ( 90 lessons)
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