The propagation of light Flashcards
What is a wavefront?
The wave peak perpendicular to the propagation direction
What does a ray show?
The direction of propagation
What is the refractive index of a material?
n=c/v
Where v is the speed of light in the material
What is Snell’s law?
n1 sin(θi) = n2sin(θt)
When do we get a reflected ray?
When n1 does not equal n2
What is total internal reflection?
Occurs when n2<n1 and there is no transmitted ray so the incident ray is ‘trapped’ in the material
What is the critical angle?
The angle at which an incident ray must be for TIR to occur
θc=sin^-1(n2/n1)
When is the reflected ray linearly ploarised?
When the angle between the reflected ray and transmitted ray is 90 degrees
Here θi=θp
What is the polarisation angle?
tan(θp)=n2/n1
What is the transmission coefficient for light?
T=4n1n2/(n1+n2)^2
What is the reflection coefficient for light?
R=( (n1-n2)^2 )/( (n1+n2)^2 )
