Presentation on theme: "Laws of Reflection From the Activity you performed, when you shine an incident light ray at a plane mirror, the light is reflected off the mirror and forms."— Presentation transcript:
1Laws of ReflectionFrom the Activity you performed, when you shine an incident light ray at a plane mirror, the light is reflected off the mirror and forms a reflected ray.This behaviour leads to the 2 laws of reflectionThe angle of incidence is equal to the angle of reflectionThe incident ray, the reflected ray, and the normal all lie in the same plane.
4Reflecting Light Off Surfaces When a series of parallel incident rays strike a flatreflective surfacethe incidence angles are all identicalangle of reflection will also be identicalreflected raysIncident rays
5The reflected rays will be reflected in many directions. If parallel incident rays were directed at an irregular surface, they will have different incidence angles.The reflected rays will be reflected in many directions.This is known as diffuse reflectionIncident raysReflected rays
6Reflection and Dyslexia People with dyslexia have difficulty reading printcomplain about the glare off white paperthere is too much reflected lightcondition can be helped by the use of coloured filtered glasses
7Using Light Rays to Locate an Image Light rays and the laws of reflection help determine how and where an image is formed in a plane mirror.REFLECTION is the bouncing back of light rays from a surface
8We all know that light travels in a straight line. When your eyes detect reflected light from plane mirrors, your brain projects the light rays back in a straight line.
9Types of ImagesReal Images- mirrors can produce images that can be projected on a screen. A real image is ALWAYS inverted and appears in front of the mirror.
10Virtual Image- mirrors can also produce images that cannot be projected on a screen. A virtual image is ALWAYS upright and appears behind the mirror.
11Locating images in a Plane Mirror reflectedmirrorincidentobjectImage of object
12Locating Images in a Plane Mirror From the top of the object draw 2 incident raysFrom mirror draw 2 reflected raysextend reflected rays behind mirrorwhere the extended lines cross, behind the mirror, the image formsrepeat above steps for bottom of object
13Locating Images in a Plane Mirror Is there any easier way?Of course...Draw line & measureRepeat lines behind mirror2cm2cmobject3.5cm3.5cmmirror
14Locating Images in a Plane Mirror From top of object, draw a line perpendicular to mirror (along normal)measure the distance of this line and extend the line, the same distance, behind the mirrorrepeat this step from the bottom of the objectfor complicated objects, draw more than two lines2 cm3.2 cm2 cm
15Steps for drawing Plane Mirror Ray Diagrams: 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.
16Ray Diagram Using 2 Points: Perpendicular rayReflectedrayIncident ray
17Example:Let’s draw the letter P together on the boardP ?
18Lets Practice!!Using the information provided, draw these 2 images using the principles of reflection off a PLANE MIRROR.Use at least 3 points off of the object.
19Types of MirrorsPlane Mirror- a flat mirror that reflects light rays in the same way that they approach the mirror.Concave Mirror- a converging mirror where light rays that strike the mirror surface are reflected so they converge or “come together”, at a point.
203. 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.
21S.A.L.T SALT is used to describe images formed by mirrors. S- Size: compared to original object is it same size, smaller or bigger?A- Attitude: which way the image is oriented compared to the original object (upright or inverted).L- Location: location of the image (in front or behind the mirror).T- Type: is the image a real image or virtual image?
22PLANE MIRRORS Characteristics of a plane mirror image: Object size= Image SizeObject distance from mirror= image distance from mirrorAttitude (orientation) is ALWAYS uprightALWAYS forms a virtual imageImage is reversed- left to right
23The 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.AMBULANCE