W. Sautter 2007

NormalLine

NormalLine

i

r i

r

Glassn = 1.5

Airn =1.0

r = angle of refraction

i = angle of incidence

Light travels more slowlyin glass than air and

bends towards the normalwhen entering glass from air

Light moving fromglass to air

increases speedand bends awayfrom the normal

Virtual focusFocus = -

Can form only virtual,Erect and reduced

images

Principlefocus

Parallel rays

Focus = +Can form real images(enlarged or reduced

& inverted) orEnlarged virtual images

NormalLine

r i

Incidentray

Reflectedray

Mirror surface

Angles are ALWAYS measured from the NORMAL LINE

Parallel rays

Reflected rays

RealFocus

Focal length = +Forms real, inverted,Reduced or enlarged

Image. Also formsVirtual, erect,

Enlarged images.

Parallel rays

Reflected rays

Virtual focus

Focal length = -Forms only virtual,

erect, reduced images betweenthe virtual focus and the mirror.

Waves from aDistant source = crest

= trough

Barrier withTwo slits

In phase wavesEmerge from slits

Constructive interference

Destructiveinterference

Wavelength

Frequency

Velocity Wavelength

Frequency

Velocity

vx =

VISIBLE AND INVISIBLE LIGHT• MOST “LIGHT” IS NOT VISIBLE TO THE HUMAN EYE !

• ONLY ABOUT 7 % OF THE KNOWN KINDS OF LIGHT CAN BE SEEN WITHOUT SPECIAL INSTRUMENTATION.

POTASSIUM METALBATTERY

VOLTMETERPHOTONS

PICKUP

WIREELECTRONS

ONLY CERTAIN MINIMUM FREQUENCIES OF LIGHT

FREE THE ELECTRONS FROM THE METAL

(ONLY PHOTONS WITH ENOUGH ENERGY)

THE PHOTOELECTRIC EFFECT EXPERIMENT

Parallel ray

Focal rayRay thru 2f focus (f)2 fvertex

Reflects thruThe focus

Reflects parallelTo principal axis

Principal axis

Reflects Back Into itself

Parallel ray

Focal rayRay thru 2f f2 f

Image is:RealInvertedReducedAppears between f & 2f

Object beyond 2f

Image is:RealInvertedSame sizeAppears at 2f

Parallel rayFocal ray

ray thru 2f f2 f

Object at 2f

Image is:RealInvertedEnlargedAppears beyond 2f

Parallel ray

ray thru 2fFocal ray

2 f f

Object betweenf and 2f

Image is:VirtualErectEnlargedAppears behind the mirror

Parallel ray

ray thru 2f

Foc

al r

ay

2 f f

ray thru 2f

ApparentConvergence

Of rays

Object inside focus

Angle of incidence = Angle of Reflection For each ray

Dotted lines Shows the Apparent

Ray source

Parallel rays

Reflected rays

Virtual focus

Focal length = -Forms only virtual,

erect, reduced images betweenthe virtual focus and the mirror.

Dotted lines Shows the ApparentRay focus

Apparent Convergence of rays

2 f(f)

Focal ray

Parallel rayRay thru 2f

Image is:VirtualErectReducedAppears behind the mirror

focus (f)focus (f) 2 f2 fx x x x

Parallel rayPasses thruThe focus

Focal rayRefracts parallelTo principal axis

A ray thru theCenter of the

lenses

Remains unbent

Parallel ray

focus (f)focus (f) 2 f2 fx x x x

Focal ray

Image is:RealInvertedReducedAppears between f and 2f

Object beyond 2f

focus (f)focus (f) 2 f2 fx x x xFocal ray

Parallel ray

Image is:RealInvertedSame sizeAppears between f and 2f

Object at 2f

focus (f)focus (f) 2 f2 fx x x xFocal ray

Parallel ray

Image is:RealInvertedEnlargedAppears beyond 2f

Object betweenf and 2f

focus (f)focus (f) 2 f2 fx x x x

Image is:VirtualErectEnlargedAppears on sameSide as Object

ApparentConvergence

Of rays

ObjectInsidefocus

focus (f) 2 f2 f focus (f)

Apparent ray convergenceIs on same side as object

f2 f f 2 fFocal ray

Parallel ray

Ray thru center

Image is:VirtualErectReducedAppears on sameSide as object

Wave A

Wave A

Wave A

Wave B

Wave B

Wave B

Constructive interference

Destructive interference

Partially Constructive interference

Waves from aDistant source

= crest = trough

Barrier withTwo slits

In phase wavesEmerge from slits

Constructive interference

Destructiveinterference

d

0

1

1

2

2

m

SPECTRAL

ORDER

m = spectral order The bright central band is zero and each bright band

to the right or left is counted by consecutive integers 1,2,3 etc.

d = distance separating the slits (meters)= wavelength of light in meters

= angle between the zero band and the spectral band m

Each edge of the slit creates a new wave front. The

two new waves then interfercreating a diffraction pattern

m = spectral order The bright central band is zero and each dark band

to the right or left is counted by consecutive integers 1,2,3 etc.

s= slit width (meters)= wavelength of light in meters

= angle between the zero band and the spectral band m