Unit 3 - Polarization Flashcards
Definition of a plane polarised wave
An electromagnetic wave whose electric field vector at all times lies in a fixed plane which contains the direction of propagation.
Explain the difference between polarised and unpolarised light
With linearly polarised light the oscillations of the electric field vector are restricted to one plane whereas with unpolarised light the electric field vector oscillates in all directions perpendicular to the direction of wave propagation.
Describe how light can be polarised using a Polaroid filter
A polaroid filter will only transmit vibrations of the electric field vector in one plane.
Describe how a polariser and analyser can prevent the transmission of light.
A polariser and analyser are placed at right angles to each other. They are both placed perpendicular to the direction of transmission. The polariser will only transmit vibrations of the electric field vector in one plane, the analyser will absorb these vibrations since they are all perpendicular to its axis of transmission.
Explain how sunglasses can remove glare.
When light is reflected from a horizontal surface, such as water, the light will be polarised. The polariod in the sunglasses acts as an analyser and cuts out a large part of the reflected light.
What is the polarising angle
When light is incident at a boundary between air and an electrical insulator, the polarising angle is the angle of incidence in air which causes the reflected light to be linearly polarised.
