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Plane Mirror
di = distance of image from mirror
do = distance of object from mirror
hi = height of image
ho = height of object


  • We see light as if it travels in a straight line

Law of Reflection
Ѳincidence= Ѳreflection
external image lr.gif

Image retrieved from: www.physicsclassroom.com
Images formed by plane mirrors

*think about your image in a mirror
1. Image is upright (as opposed to inverted)
2. Image is the same size as the object (image is neither magnified nor reduced)
hi/ ho = 1
3. Image is as far behind the mirror as the object is in front of it
do=di

How to draw an image
Use at least 2 light rays originating from a point on the object and find where the reflected rays converge (meet). This point will be where the same point on the image appears to be.
Why is an image formed?
external image ifpm.gif

Image retrieved from: www.physicsclassroom.com

Is the image real or virtual?
Virtual- not created by actual light rays (just projections of real light rays)
Real-formed by actual light rays

· Focal point- when light rays parallel to the principle axis reflect off a curved mirror, they will converge at the focal point
general.png
(1/do) + (1/di) = (1/f)
M= (hi/ho) = (-di/do) *M= magnification
f = R/2
Convenient Light Rays
· p-ray =parallel then through focal point
· f-ray= through focal point then parallel
· m-ray= middle

1) Concave Mirror
a. Object is outside the focal point
Image is…
Inverted, reduced, real
CMOF.png


b. Object is inside the focal length
Image is…
Upright, magnified, virtual
CMIF.png


2) Convex Mirrors (Diverging Mirror)
Image is…
Virtual, upright, reduced
CNVXM.png


*focal length is negative because the focal point is opposite the side of the reflective surface
*any measurements behind the mirror will be negations

  • FOCAL LENGTH WILL ALWAYS BE NEGATIVE FOR DIVERGING LENSES AND MIRRORS

1)
Double Convex Lens (Converging Lens)
a. Object outside focal length
Image is…
Inverted, magnified, real
DCNXOF.png


b. Object within focal length
Image is…
Upright, magnified, virtual

DCNXOF.png
2) Double Concave Lens (Dverging Lens)
Image is…
Virtual,reduced, upright

DCNC.png

Refraction
The “bending of a wave when it travels from one median to another at an angle (this bending occurs as waves travel at different speeds in different media)

Index of refraction (n)
A measure of how optically dense a material is.
nvacuum=1.000000
nair=1.0003

speed of light in a medium
vn=c/n *c= 3x108 m/s

Snell’s Law
n1sinΘ=n2sinΘ

1. n1< n2 - light will bend toward the normal
REFR1.png

2. n1>n2 – Light will bend away from the normal
REFR2.png
Note that the light will bend towards the direction that the arrow in the <> is pointing to.

Critical angle: angle of incidence such that the angle of refraction is 90°

CRA.png
In this scenario all of the light is reflected within the water, such that none escapes to the air.










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