Light and Reflections

Students will be able to Compare different types of reflectionContrast different types of mirrorsUnderstand index of reflectionContrast different types of lenses

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Reflections

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Reflection of Light Rays

Ray – Straight line wave to represent light

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Reflection of Light Rays

Two types of ReflectionRegular

Light hits a smooth surfaceAll rays reflected at same angleSharp image

DiffuseUneven surfaceEach ray reflects differently

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Two Types

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Plane Mirrors

Flat sheet of glass with a smooth silver coatingWhat you see in mirror is virtual image

Appears to be behind the mirrorSame size and uprightRight and left sides are reversed

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Plane Mirror

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Concave Mirrors

A mirror with a surface that curves inward like a bowl

Optical axis =Imaginary line that cut mirror in half

Focal point = Point where rays meetThe more curved then the closer the focal point

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Concave Mirrors

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Concave Mirrors

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Concave Mirrors

Real image is produced when rays meetAlways upside downCan be larger or smaller

Virtual image if inside focal pointAlways right side upAlways larger

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Concave Mirrors

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Convex Mirrors

Mirror curves outwardAlways virtual imageAlways smaller

Used in side mirrors of cars Picture large world in small mirrorProblem is that everything is small

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Convex Mirrors

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Refraction

Light waves bend when they enter a new medium at an angle

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Index of Refraction

Measure of how much light bendsThe higher the number the more it bends light

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Prisms and Rainbows

Longer wavelength bends least (red on top)Short wavelength bends more (violet on bottom)

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Mirages

Temperature changes will cause light to change speed (light wave moves faster in when hot)

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Lenses

Lens = Curved piece of glass to refract light

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Convex LensThicker in the center than the edges

Can produce virtual or real images depending on location

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Convex Lens

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Concave Lens

Thicker on the edges than in the middleOnly virtual images

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Quiz

Homework

Describe one type of mirrors and one type of lens