PROPERTIES OFLIGHT• 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.
RAY AND BEAM OFLIGHT• A ray of light is indicated by a single straight line.• A collective light rays is called a beam of light.
REFLECTION OFLIGHT• 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
REFLECTION OFLIGHT• 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.
THE LAWS OFREFLECTION• 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.
PLANE MIRRORCharacteristics of an image formed in a plane mirror:1. Laterally inverted2. Same size as the object3. Upright4. Same distance of object and image from the mirror5. Virtual (cannot be captured on screen)
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.
HOW LIGHT RAYTRAVELS• 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
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
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.