L1 Basics Of Light Flashcards
Define source
Any object that emits radiation
Define point source
- infinitely small as it is far away
Define Extended source
Source that has a certain area
Define Wave motion
Light propagation (the way it travels) For physical optics
Define Wavefront
An imaginary line joining all peaks / points in same phase of a wave
Define Rays
Shows light propagation in geometric optics
Normal to wave front
Define Axis
Horizontal line passing through point source
Define pencil
All rays ( convergent, divergent, parallel) coming from a point source
Sign convention rule
Light travels from left to right
How to measure radii of wavefront
From wavefront to Source / image
Positive vergence = convergence
Negative vergence = divergence
Zero vergence = parallel
Define interface
The boundary where light travels from one optical medium to another optical medium
Define critical angle
The incident angle that yields a refracted angle of 90°
define and calculate for refractive index
- light travelling at different velocities depending on the media
- the denser the medium, the slower light travels
- velocity in vacuum / velocity in medium
refractive index for water and human cornea
1.333 and 1.376 respectively
explain law of reflection
- angle i = angle r
- incident ray, reflected ray, normal all lie on same plane
