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Images on a Plane Mirror. Using 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. We all know that light travels in a straight line.
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Using 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.
We 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.
same angle • Laws of Reflection- Review • When a light ray is incident upon reflection surface, the angle of reflection is equal to the angle of incidence. • Both angles are measured relative to the normal. • The incident ray, reflected ray and normal all lie in the SAME plane. Normal Reflected ray Incident ray
Types of Images • Real 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.
Virtual Image- mirrors can also produce images that cannot be projected on a screen. A virtual image is ALWAYS upright and appears behind the mirror.
Types of Mirrors • Plane 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.
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.
S.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?
PLANE MIRRORS • Characteristics of a plane mirror image: • Object size= Image Size • Object distance from mirror= image distance from mirror • Attitude (orientation) is ALWAYS upright • ALWAYS forms a virtual image • Image is reversed- left to right
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. AMBULANCE
Steps for drawing Plane Mirror Ray Diagrams: • 1. A ray that strikes perpendicular to the mirror surface, reflects perpendicular to the mirror. Thereflected 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.
Ray Diagram Using 2 Points: Perpendicular ray Reflected ray Incident ray
Example: • Let’s draw the letter P together on the board P ?
Lets Practice!! • Using the handout provided, draw these 2 images using the principles of reflection off a PLANE MIRROR. • Use at least 3 points off of the object.
HOMEWORK: P. 493 #1-4,6, 7 and 11