This document discusses key properties of light, including that it travels in straight lines at 3x10^8 m/s in a vacuum. It describes rays and beams of light and the reflection and refraction of light, including the laws of reflection. Reflection is when light bounces off surfaces, and refraction is when it bends when moving between materials of different densities. Refractive index measures the bending of light, and refraction makes objects appear at a different depth than their real depth under water.

1. LIGHT

2. PROPERTIES OF
LIGHT
• Light travels in straight lines.
• It is a form of energy.
• It travels at a speed of 3 x 108 m s-1 in vacuum.
• When light hits an object, it can be reflected or refracted.

3. RAY AND BEAM OF
LIGHT
• A ray of light is indicated by a single straight line.
• A collective light rays is called a beam of light.

4. REFLECTION OF
LIGHT
• Reflection is light being bounced off after hitting an
opaque surface.
• Reflection allows us to see objects in our surroundings.
• In reflection of light, there are:
- Incident ray: Light ray coming towards the surface
- Reflected ray: Light ray bouncing off the surface

5. REFLECTION OF
LIGHT
• The type of reflection, regular or diffused is affected by the
type of surface.
- Regular reflection: When the light rays are incident on a
smooth surface, they are reflected on a regular manner.
- Diffused (or scattered) reflection: When the light rays are
incident on a rough surface, they are reflected in a
diffused or scattered manner.

6. THE LAWS OF
REFLECTION
• The 2 laws of reflection are:
- Angle of incidence is equal to angle of reflection.
- In a reflected diagram, the incident ray (i), the reflected ray
(r) and the normal must lie in the same plane.

7. PLANE MIRROR
Characteristics of an image formed in a plane mirror:
1. Laterally inverted
2. Same size as the object
3. Upright
4. Same distance of object and image from the mirror
5. Virtual (cannot be captured on screen)

8. REFRACTION
• Refraction is the bending of light rays when they travel
from one transparent medium to another.
• Refraction is caused by a change in the speed of light rays
when they travel in the media of different densities.
• Refraction of light can only take place in transparent
media such as air, water, vacuum(in space), glass and
diamond.
• Light travels at different speeds in different media.
- In a less dense medium, the speed of light is faster.
- In a denser medium, the speed of light is slower.

9. HOW LIGHT RAY
TRAVELS
• From a less dense medium to a denser medium:
- Light ray bend towards the normal.
• From a denser medium to a less dense medium:
- Light ray bends away from the normal

10. REFRACTIVE INDEX
• It is a measure of the bending of light ray when travelling
from one medium into another.
• Formula: n = sin i/ sin r

11. EFFECT OF REFRACTION
(APPARENT AND REAL DEPTH)
• Real depth is the actual depth or position of the object
under water.
• Apparent depth is the depth or position perceived by an
observer due to refraction of light.
• The apparent depth is less than the real depth in the effect
of refraction.