Reflection and RefractionReflection and Refraction

May 28, 2013May 28, 2013

ObjectivesObjectives

1.1. Predict the path of reflected light striking a Predict the path of reflected light striking a reflective surfacereflective surface

2.2. Define virtual imageDefine virtual image

3.3. Give examples of refraction and describe Give examples of refraction and describe how it workshow it works

Law of ReflectionLaw of Reflection

The angle of reflection equals the angle of The angle of reflection equals the angle of incidence incidence

– Angle of Incidence – the angle at which the Angle of Incidence – the angle at which the object hits a flat surface (i)object hits a flat surface (i)

– Angle of Reflection – the angle at which it Angle of Reflection – the angle at which it rebounds off the flat surface (r)rebounds off the flat surface (r)

– Normal – imaginary line that extends Normal – imaginary line that extends perpendicular to the flat surfaceperpendicular to the flat surface

Flat mirrors – plane Flat mirrors – plane mirrors show this mirrors show this perfectlyperfectly

Virtual ImagesVirtual Images

When you look at a mirror it appears that When you look at a mirror it appears that you are behind that mirror in exactly the you are behind that mirror in exactly the same position same position

It is the reflection that we see, but our minds It is the reflection that we see, but our minds perceive it not as a reflection, but as coming perceive it not as a reflection, but as coming out from the mirrorout from the mirror

Curved mirrorsCurved mirrors

Law of Reflection still holds, but the sizes Law of Reflection still holds, but the sizes and distance of the object and image are not and distance of the object and image are not equalequal

Convex mirror – curves outward, virtual Convex mirror – curves outward, virtual image is smaller and closerimage is smaller and closer

Concave mirror – curves inward, virtual Concave mirror – curves inward, virtual image is larger and further awayimage is larger and further away

What evidence can you use to support the What evidence can you use to support the claim that the frequency of light does not claim that the frequency of light does not change upon reflection? (pg. 255)change upon reflection? (pg. 255)

If you took a picture of your image while If you took a picture of your image while standing 2 m in front of a plane mirror, what standing 2 m in front of a plane mirror, what distance should you set your camera to distance should you set your camera to provide the sharpest focus? (pg. 255)provide the sharpest focus? (pg. 255)

Diffuse ReflectionDiffuse Reflection

Light incident on a rough surface reflects in Light incident on a rough surface reflects in many directionsmany directions

RefractionRefraction

The bending of light due to changing speed, The bending of light due to changing speed, passing from one medium to anotherpassing from one medium to another

When light slows down (goes into water) it When light slows down (goes into water) it refracts toward the normalrefracts toward the normal

When light speeds up (goes into air) it When light speeds up (goes into air) it refracts away from the normalrefracts away from the normal

Why is it more dangerous to drive a car of a Why is it more dangerous to drive a car of a rainy day? (pg. 257)rainy day? (pg. 257)

If the speed of light were the same in all If the speed of light were the same in all media, would refraction still occur when light media, would refraction still occur when light passes from one medium to another? (pg. passes from one medium to another? (pg. 258)258)