LIGHT notes for physics

LIGHT
Key notes:
1. The laws of reflection:
a) The incident ray, the normal and the reflected ray all lie on the same plane,
b) The angle of incidence = the angle of reflection.
2. The image formed by a plane mirror:
a) is virtual,
b) is upright,
c) is laterally inverted,
d) has the same size as the object,
e) is located at the same distance behind the mirror as the object is in front of it.
3. Refraction is the bending of a ray of light as it moves from one medium into
another. This is due to a change in the speed of light.
4. Light is refracted towards the normal when it travels from an optically less
dense medium into an optically denser medium.
5. A thin converging lens converges rays parallel to the principal axis to a point
on the principal axis called the principal focus.
6. The focal length is the distance between the principal focus and the optical
centre of the lens.
7. Rays that pass through the optical centre of the lens are not deviated.
8. The action of a converging lens is based mainly on refraction.
9. The nature of the image formed by a convex lens is different depending on the
object distance, u.
Formulas:
 LAWS OF REFRACTION
Refractive index, n = sin i / sin r
Refractive index = speed of light in vacuum / speed of light in medium
 REAL & APPARENT DEPTH
Refractive index, n = real depth / apparent depth
= H / h