4.8 Polarisation Flashcards
What is a polarised wave?
Wave in which the displacement remains always in a single plane, this is a property of TRANSVERSE waves only.
What happens when light is polarised?
Light is a transverse wave with electric and magnetic fields oscillating at right angles to one another and to the direction of energy transfer. When the wave is polarised it only oscillates in a single plane.
How can light be polarised?
By passing it through a polariser - molecular structure only allows transmission of the component of the electric field parallel to a particular direction.
What happens to the intensity of light when it is passed through a polariser?
Transmitted itnensity is half the incident intensity. I = Io/2
What happens when polarised light is passed through two polarisers whose transmission axis is at right angles to the direction of the electric field?
No electric field is transmitted and so no light passes through.
What is Malus’ law?
I = Iocos^2@
What happens to light when it is reflected off a surface?
Light with electric field parallel to the surface is reflected more efficiently than light with electric field in other directions - result is reflected light that is mainly horizontally polarised.
