Reflection & Mirrors

Recap:Diffuse reflection: gives a blurry image (or none at all)

Specular reflection: gives a clear image

Mirror types:PLANE CONVEX CONCAVE

Plane Mirrors• The image formed by plane

mirrors can only be seen behind the mirror.

• This is known as a virtual image.

• Image is the same size as the object.

• Only the right and left of the image is changed.

Curved Mirrors• Curved mirrors can be either– concave (making a little cave) – Causes light to converge

– convex (vexing out in the middle) – Causes light to diverge

Law of Reflection

Ray Diagrams

• Show path of light from object mirror away from mirror

• Allows you to determine the location and properties of an image formed by a mirror or lens

Ray Diagram: Basic set-up

** r = 2f

mirror

Principal axisC

(center of curvature)

F(focal point)

f(focal length)

r(radius of curvature)

Ray Diagrams: images

• REAL vs. VIRTUAL• UPRIGHT vs. INVERTED• SAME SIZE, SMALLER, ENLARGED

COMPARE IMAGE TO ORIGINAL OBJECT

Real or Virtual

Real images can project on a screen

Virtual images can only be seen in a mirror

Upright or Inverted

Upright images are oriented the same as the object

Inverted images are oriented in the opposite direction as the object

Reduced or Enlarged

Reduced images are smaller in size than the object

Enlarged images are larger in size than the object

Get ready to draw diagrams…

• Take 2 different colored pencils• Take a slice of index card/Ruler– This will be your straight-edge– PUT YOUR NAME ON IT & KEEP IT– Decorate it if you want to

• Take a notes packet

• Ready? Let’s do this!

Concave Mirror A

F

Step 1: draw horizontal ray from top of object to mirrorStep 2: draw reflected ray from point where ray hits mirror through focal pointStep 3: draw second ray from top of object through focal point to mirrorStep 4: draw reflected ray from point where ray hits mirror horizontally backStep 5: draw image from principal axis to intersection of reflected rays

Image is:REALINVERTEDLARGERFARTHER

Concave Mirror B

F

Step 1: draw horizontal ray from top of object to mirror Step 2: draw reflected ray through focal point Step 3: draw second ray from focal point, through top of object, to mirror Step 4: draw horizontal reflected ray Step 5: continue both reflected rays behind mirror as DASHED LINES Step 6: draw image from principal axis to intersection of reflected rays

Image is:VIRTUALUPRIGHTLARGERFARTHER

Convex Mirror

F

Step 1: draw horizontal ray from top of object to mirror Step 2: draw reflected ray from focal point through point where ray hit mirror and out Step 3: draw angled ray, aimed at focal point, to mirror Step 4: draw horizontal reflected rayStep 5: continue both reflected rays behind mirror as DASHED LINES Step 6: draw image from principal axis to intersection of reflected rays

Image is:VIRTUALUPRIGHTSMALLERCLOSER

• Questions?

• Begin optics packet!