Light Flashcards
Define ‘reflection’
The rebounding of light at a surface.
Define ‘incident ray’ of reflection
Light ray that hits the reflecting surface.
Define ‘reflected ray’ of reflection
Light ray that bounces off the reflecting surface
Define ‘angle of incidence’ of reflection
The angle between the incident ray and the normal.
Define ‘angle of reflection’
The angle between the reflected ray and the normal.
Define ‘normal’
The perpendicular to the reflecting surface at the point of incidence.
State the relationship between ‘i’ and ‘r’ for reflection
The ‘i’ is equal to the ‘r’.
Define ‘refracted ray’
The light ray that enters a medium and undergoes a change of direction.
Define ‘incident ray’ of refraction
The light ray that striked a surface.
Define ‘angle of incidence’ of refraction
The angle between an incident ray and the normal at the point of incidence.
Define ‘angle of refraction’
The angle between a refracted ray and the normal at the point of incidence.
Define ‘optical medium’
A material through which light can pass through.
Define ‘interface’
The surface separating 2 phases of matter.
What is the speed of vacuum?
3x10^8 m/s
What is the relationship between sin i and sin r?
n ( refractive index ) = sin i / sin r
What is the refractive index of an optical medium?
The ratio of the speed of light in vacuum to the speed of light in the medium.
n = c / v
How does light bend as it travels from one optical medium to another?
Bend towards normal when it enters an optically denser medium.
Bend away from normal when it enters an optically less dense medium.
Define ‘critical angle’
The angle of incidence in an optically denser medium for which the angle of refraction in the optically less dense medium is 90 degree.
Define ‘total internal reflection’
The complete reflection of a light ray inside an optically denser medium at its boundary with an optically less dense medium.
Conditions required to undergo total internal reflection.
- Light ray in an optically denser medium strike its boundary with an optically less dense medium.
- Angle of incidence is greater than the critical angle of the of the optically denser medium.
Formula for critical angle
sin c = 1 /n
Define ‘focal length’
The distance between the optical centre C and the focal point F.
Define ‘focal plane’
The plane that passes through the focal point F and perpendicular to the principal axis.
Define ‘optical centre’
Midpoint between surfaces of the lens on its principal axis.
