# Mirrors - Baltimore Polytechnic Institute Do Now: At the interface between two materials, a light ray is at an angle of incidence of 45 on a side with an index of refraction of 1.11. The light is at an angle of 34.49 on the other side of the interface. What is the index of refraction on the other side?

Extra Credit: Take your quiz home and correct your mistakes. Turn it in on Monday and half of the points will be added to your quiz grade (ex. If you got a 60, you would get an 80) if all work is correct

Do Now (5/10/12) (4 min): 1.What are some things you know about mirrors? 2.What happens when you go into a House of Mirrors?

Mirrors 5/6/11 Plane Mirror A flat, smooth surface from which light is reflected *the Law of Reflection applies

Plane Mirror Images Produce virtual images Virtual images: form in locations where light does not actually reach. left-right reversal

upright Plane Mirror Images d i d o hi ho di = image

distance do = object distance hi = image height ho = object height Example:

If Suzie stands 3 feet in front of a plane mirror, how far from the mirror will her image be located? d i d o 3 ft Curved Mirrors

spherical mirrors: mirrors that have a spherical shape. Concave: mirror on the inside of the sphere Convex: mirror on the outside of the sphere. Concave

f=focal point C=radius of curvature C f 2 The Mirror Equations M= magnifcation

Example: di = 10 cm do = 20 cm

f=? 1 1 1 f do di

1 f 1 f 1 f f 1 1

20 10 . 05 . 1 . 15 6 . 667 cm Practice: Complete the first two

short answer and the first 7 problems After, you may work on your next art piece Practice: Complete the first two short answer and

the first 7 problems After you may work on quiz corrections Do Now: 5 min f= 10 cm do = 20 cm di =?

Curved Mirrors Concave mirrors can produce real images (as well as virtual images). Real image: light actually passes through the image location. Graphical Method of Finding the Image

An incident ray traveling parallel to the principal axis will pass through the focal point upon reflection. An incident ray passing through the focal point will travel parallel to the principal axis upon reflection.

Step-by-Step Method for Drawing Ray Diagrams 1. From the top of the object draw two incident rays traveling towards the mirror: Ray 1: passes through the focal point on the way to the mirror Ray 2: travels parallel to the principal axis

Ray 2 Ray 1 Step 2: Once these incident rays strike the mirror, reflect them according to the two rules of reflection for concave mirrors.

Extend the rays past their point of intersection. Step 3: Mark the image of the top of the object.

Step 4: Fill in the image. If the bottom of the object lies upon the principal axis, the image of this point will also lie upon the principal axis. Ray Diagram for Virtual Image

Ray Diagram for Object at Focal Point Image is not formed Practice: Complete one side of the

Curved Mirror worksheet Do Now: Draw a ray diagram and locate the image: C F

Pop Quiz: Copy the following diagram exactly onto your paper. Draw a ray diagram and locate the image: C

F do MirrordProperties m Single i do>C C>di>f

Reduced, inverted Enlarged, inverted C>do>f di>C f>do d

d i o (negativ Enlarged e) imag e Real

Real Virtual Draw ray diagrams on both sides; label image characteristics from chart on Practice:

Complete one side of the Curved Mirror worksheet. *if you were not here Friday complete two ray diagrams then complete the first three problems on your Intro to Mirrors Worksheet Classwork: