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Geometric Optics vs. ‘the wave’. ‘plane’ traveling wave. ( Apple >> l ). A light ray: IN. Rough surface. A light ray: IN. Diffuse reflection:. A light ray: IN. Reflected light rays: OUT. Distinguishing Objects. Diffuse reflection. Diffuse reflection:. Diffuse reflection.
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Geometric Optics vs. ‘the wave’ ‘plane’ traveling wave
A light ray: IN
Rough surface A light ray: IN Diffuse reflection:
A light ray: IN Reflected light rays: OUT
Distinguishing Objects Diffuse reflection
Diffuse reflection: Diffuse reflection
No focusing: Belly and nose undistinguishable!
Use a lens to ‘focus’: Belly and nose distinguished !
Use a lens to ‘focus’: Belly and nose distinguished !
How to focus divergent light rays? Start: Use reflection off of smooth surfaces (mirrors) of special shapes. Flat mirror
Flat mirrors and virtual images: “Virtual” image !
Where is F ? • must • be “small”!
Image ? Object
Image ? Object
Image ? Object
Image ? Object Image
Image ? Object Image
Image ? Object Image
Image ? Object Image
For a concave mirror: InvertedReal Image Convention: m < 0 for inverted image!
Example: A cute, baby chick is standing 10 ft in front of a concave mirror of radius 5 ft. Where is its image and how big?
Example: A cute, baby chick is standing 10 ft in front of a concave mirror of radius 5 ft. Where is its image and how big?
Example: Now, the cute, baby chick is standing 5 ft in front of a concave mirror of radius 5 ft. Where is its image and how big?
Example: Now, the cute, baby chick is standing 5 ft in front of a concave mirror of radius 5 ft. Where is its image and how big?
Example: Now, the cute, baby chick is standing 3 ft in front of a concave mirror of radius 5 ft. Where is its image and how big?
Example: Now, the cute, baby chick is standing 3 ft in front of a concave mirror of radius 5 ft. Where is its image and how big?
Example: Finally, the cute, baby chick is standing 1 ft in front of a concave mirror of radius 5 ft. Where is its image and how big? DEMO
Example: Finally, the cute, baby chick is standing 1 ft in front of a concave mirror of radius 5 ft. Where is its image and how big? “Virtual” image ! DEMO
‘Focal length’ ? • must • be small!