uses of mirrors & lenses what are some commercial uses of lenses? what are some commercial uses...
TRANSCRIPT
Open to 5.2
Can you see the buck?(not the doe)
Uses of Mirrors & Lenses
What are some commercial uses of lenses? Glasses/ Contacts Projectors Cameras Microscopes Telescopes Binoculars*
Camera
Telescope
Clip
Binoculars
Projector
Microscope
Clip
Mirrors & Lenses
Convex
Concave
Converging – light rays come together
Diverging – light rays spread out
Mirrors & Lenses
Types of Images
Virtual Image right-side-up cannot be projected on a screen
Real Image upside-down can be displayed on a screen*
Image formation
Distance affects the angle of view
Far away- small angle of view allows very little detail to be seen
Closer- larger angle of view creates more details to be seen
Ray Diagram Setup
Principal axis- line in a lens that joins the centers of curvature of the lens surface
Ray Diagram Setup
Focal point- point at which a beam of parallel light, to the principal axis, converges
Ray Diagram Setup
Focal Plane- all possible points on a plane for the location of the focal point
Ray Diagram Setup
Focal length- distance between center of lens and its focal point
Ray Diagrams:
Copy the instructions on the next few slides and then we will look at the rules in a virtual “draw”.
How to draw a mirror ray diagram:
1. parallel to the axis then go through the focal point.
2. to the center of the mirror then out at the same angle.*
Let’s draw a correct ray diagram
The scope of vision looks like this in yellow.
The first blue ray goes from the top of the object – parallel to the “principal axis” and comes back at the same angle (90)
Let’s draw a correct ray diagram
There is no focal point on a flat mirror.
If we are wanting to begin at the top of the ‘P’ - the angle is whatever you choose with the red arrow
http://www.regentsprep.org/Regents/physics/phys09/bcraytrace/default.htm
How to draw a lens ray diagram:
1. parallel to the axis then to through the focal point.
2. straight through the center of lens. *
http://www.regentsprep.org/Regents/physics/phys09/bcraytrace/default.htm
Let’s draw a correct ray diagram
Let’s draw a correct ray diagram
More practice
More practice
Mirror & Lens Equation
Focal length
io ddf
111
distance to imagedistance
to object
do = 15.5 cm
f = 15.0 cm di = ?
io ddf
111
id
1
5.15
1
15
1
15.5
1
15
1
d
1
i
cm 654d i
Example) Mr. Nelson is showing slides to his physics class, if the slides are positioned 15.5 cm from the projector lens that has a focal length of 15.0 cm, where should the screen be placed to produce the clearest image of the slide?
Power of Eyeglasses
fP
1
Power – measured in diopters (1/meter)
focal length (m)*
P = ?f = .30 m
fP
1
30.0
1P
diopters 33.3P
Example) Beth is farsighted, so she must wear glasses to see objects close by. If her glasses have a focal length of 0.30 m, what is their power in diopters?
Image Size Magnification- image is observed
through a wider angle with the use of a lens
o
i
h
hM
Magnification
object height*
image height*
Practice Problem
As you look through your binoculars at a deer out in the field, the deer appears to be 3 m tall but the deer in real life is only 1 m tall. How much magnification do your binoculars have?
As you look through your binoculars at a deer out in the field, the deer appears to be 3 m tall but the deer in real life is only 1 m tall. How much magnification do your binoculars have?
o
i
h
hM
m
mM
1
3 xM 3
Mirror and Lens Overview
Lemony Snickets Clip
Talking on a LASER Demo
http://www.andrews.edu/phys/wiki/PhysLab/doku.php?id=lab10
lab