G t i O tiGeometric Optics

Chapter 34January 26, 2012January 26, 2012

January 26, 2012 Physics 221 1

To access the applets shown in classppGo to the Study Area on the MasteringPhysics web site.

Chapter 34January 26, 2012January 26, 2012

January 26, 2012 Physics 221 2

Sign rules for greflection and refraction..

The object distance is positive if it is on the same side of the lens/mirror as the “incoming rays” (s is positive).

The image distance is positive if it is on the same side of the lens/mirror as the “outgoing rays” (s’ is positive).

The radius of curvature of a spherical surface is positive when the Center of Curvature is on the same side as the outgoing light (R is positive).

The “lateral” magnification of a system is defined as M = image height/object height = y(image)/y(object)

January 26, 2012 Physics 221 3

Summary of Mirror Equations

January 26, 2012 Physics 221 4

January 26, 2012 Physics 221 5

January 26, 2012 Physics 221 6

January 26, 2012 Physics 221 7

Thin Lenses….converging

Thin lenses are formed byth i t ti f tthe intersection of two surfaces.

Two Spherical Surfaces

A Sphere and a plane

January 26, 2012 Physics 221 8

and diverging lenses…

January 26, 2012 Physics 221 9

Focusing properties of a thin lens

S ll’ L i b d t h i t f f th l

Parallel light enters the lens.

Snell’s Law is obeyed at each interface of the lens.

g

Light is focused to a point after the lens

January 26, 2012 Physics 221 10

Lens Conventions..The focal length is positive for a converging lens and negativefor a diverging lens.

Th bj t di t i iti if it i th id f thThe object distance is positive if it is on the same side of the lens as the “incoming rays”.

The image distance is positive if it is on the opposite side of theThe image distance is positive if it is on the opposite side of the lens from where the “incoming rays” originate.

Image distances are positive for REAL images and negative for VIRTUAL iVIRTUAL images.

The height of the image is positive if it is “upright”.

January 26, 2012 Physics 221 11

The Lens Formula…

sy

sy

fsy

fy and '

'

'

'

=−

=

yy111

solving and and for ngsubstituti '

January 26, 2012 Physics 221 12fss111get we ' =+

For thin lenses…..

111fss111 ' =+fss

Image distanceObject distance Focal distance

January 24, 2012 Physics 221 13

Image distancej

For thin lenses…..

Lateral Magnification

s 'g

ss-m =s

January 24, 2012 Physics 221 14

Lensmaker’s equation…..

( ) ⎟⎟⎞

⎜⎜⎛

=+11111 n( ) ⎟⎟

⎠⎜⎜⎝

−−=+21

' 1s

s RR

n

⎞⎛

and

( ) ⎟⎟⎠

⎞⎜⎜⎝

⎛−−=

111f1

RRn

January 24, 2012 Physics 221 15

( ) ⎟⎠

⎜⎝ 21f RR

Examples

November 22, 2011January 24, 2012 Physics 221 16

Camera

January 24, 2012 Physics 221 17

The eye

January 26, 2012 Physics 221 18

The magnifier

January 26, 2012 Physics 221 19

Microscope

January 26, 2012 Physics 221 20

Telescope

January 26, 2012 Physics 221 21