Ms Lim's Cheat Sheet : Light Flashcards
What is Light?
Light is a wave that transfers energy from one place to another.
It is part of the electromagnetic spectrum that is visible to the human eye.
What is reflection?
Reflection is the bouncing of light off a surface.
What is the law of reflection?
The angle of incidence I is equal to the angle of reflection r.
What are the 5 characteristics of an image formed by a plane mirror?
- Upright
- Same size
- Object distance = image distance
- Laterally inverted
- Virtual
What is meant by virtual image?
Image cannot be captured on a screen.
What is refraction?
Refraction is the bending of light when it enters from one medium to another.
Why does light bend?
The speed of light decreases when it enters an optically denser medium.
OR
The speed of light increases when it enters an optically less dense medium.
Define refractive index.
Refractive index is the ratio of the speed of light in vacuum to the speed of light in the medium.
n = c/v (c is the speed of light in vacuum, v is the speed of light in the medium)
Another formula to calculate refractive index.
n = sin i/sin r (i is the angle of incidence in air, r is the angle of refraction in medium)
Define critical angle.
Critical angle, c, is the angle of incidence in the optically denser medium for which the angle of refraction in the optically denser medium is 90 degree.
Define critical angle.
Critical angle, c, is the angle of incidence in the optically denser medium for which the angle of refraction in the optically less dense medium is 90 degrees.
What are the two conditions for total internal reflection?
- Light travels from an optically denser medium to an optically less dense medium.
- Angle of incidence is more than the critical angle of the optically denser medium.
