Wave Refraction

I'm preparing for my IGCSE and it is stated in the physics syllabus that:"Candidates should be able to interpret reflection, refraction, and diffraction using wave theory" and I have no idea what the 'wave theory' is....pls tell me what is it exactly. Thanks in advance
- Mohammed Yahia (age 15)
Jeddah, KSA

I think they mean the understanding of light as an electromagnetic wave, i.e. a propagating solution of Maxwell's equations. The boundary conditions on the electric and magnetic fields at the surfaces can be used to calculate the fractions of the beam that transmit or reflect. Matching the wave frequencies on both sides, with different propagation speeds,  forces the wavelengths to differ. Then matching the wavefronts determines the relation between the propagation directions on each side.

Similar arguments work for other types of waves, with different wave equations.

Mike W.

(published on 05/05/2010)