Grade 9 and 10 Science Mr.MacMillan
Types of Light Emissions 1.Light from the Sun 2.Light from Incandescence 3.Light from Electric Discharge
Uses of Fluorescence: Forensics
Money
Identify abnormal tissue
Theatre Performances
Types of Luminescence Luminescence – The emission of light by a material or an object that has not been heated; for example fluorescence
Phosphorescence Light emitted due to exposure to UV light (glow in the dark products)
Chemiluminescence Light produce by a chemical reaction without a temperature rise
Bioluminescence Light produced by a biochemical reaction
Properties of Light: Laws of Reflection Incident Ray – A ray of light travelling from a light source toward a surface Reflected ray – A ray that begins at the point where the incident ray and the normal meet Normal – A line that is perpendicular to a surface where a ray of light meets the surface
Ray Diagrams
Drawing Ray Diagrams
1.Plane Mirror- a flat mirror that reflects light rays in the same way that they approach the mirror. 2.Concave Mirror- a converging mirror where light rays that strike the mirror surface are reflected so they converge or “come together”, at a point. Types of Mirrors
3. Convex Mirrors- a diverging mirror where light rays that strike the mirror surface are reflected so that they diverge, or “go apart” and they never come to a point.
Characteristics of a plane mirror image: 1.Object size= Image Size 2.Object distance from mirror= image distance from mirror 3.Attitude (orientation) is ALWAYS upright 4.ALWAYS forms a virtual image 5.Image is reversed- left to right PLANE MIRRORS
The image in a plane mirror appears to be backwards compared to how we view the object directly. This is why the word on the front of an AMBULANCE is written backwards- so it can be read when seen in a rear-view mirror.
1. A ray that strikes perpendicular to the mirror surface, reflects perpendicular to the mirror. The reflected ray is extended beyond the mirror. 2. A ray that strikes the mirror at any angle reflects so the angle of incidence equals the angle of reflection. The reflected ray is extended beyond the mirror. Steps for drawing Plane Mirror Ray Diagrams:
Perpendicular ray Incident ray Reflected ray Ray Diagram Using 2 Points: