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Use principles of reflection and refraction to describe how lenses and mirrors work. **More good stuff available at: www.wsautter.com and http://www.youtube.com/results?search_query=wnsautter&aq=f
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W. Sautter 2007
The next slide is a quick promo for my books after which the presentation will begin
Thanks for your patience!Walt S.
[email protected] stuff at: www.wsautter.com
Books available at:www.wsautter.com
www.smashwords.comwww.amazon.com
www.bibliotastic.comwww.goodreads.com
Walt’s Books for Free!
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