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EQ: How can the phenomena of reflection, refraction, interference, and diffraction be explained?

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Reflection of Light

How do objects interact with incoming light?

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16-3-1 Reflection of Light

Objects reflect, absorb, and transmit light.

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16-3-2 Reflection of Light

light ray: a line in space that matches the direction of

wave travel or the path of photons.

Sound and Light Section 316-3-3 Reflection of Light, continued• geometrical optics: the study of light in cases in which light behaves like a ray

Sound and Light Section 316-3-4 Reflection of Light, continued• ray diagrams: geometrical

drawings that use light rays to trace the path of light when describing reflection and refraction

Sound and Light Section 316-3-5 Reflection of Light, continued

• Rough surfaces result in diffuse reflection of light in random directions

Sound and Light Section 316-3-6 Reflection of Light, continued

• Smooth surfaces reflect light rays in one direction.

Sound and Light Section 316-3-7 Reflection of Light, continued• law of reflection: the angle of incidence equals the angle of reflection

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• When light hits a smooth surface, the angle of incidence () equals the angle of reflection ( ′).

The Law of Reflection

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Mirrors

How can you see an image in a mirror?

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16-3-8 Mirrors, continued• A virtual image,

formed by flat mirrors is an image from which light rays appear to diverge, even though they are not actually focused there; a virtual image cannot be projected on a screen.

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16-3-9 Mirrors, continued• Both convex mirrors that curve out

and concave mirrors that curve in can distort images because the surface is not flat and the line perpendicular to the normal points in different directions for different parts of the mirror.

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16-3-10 Mirrors, continued

Concave mirrors, used to focus reflected light, form a virtual image behind the mirror and a real image in front of the mirror.

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16-3-11 Mirrors, continued

real image: an image that is formed by the intersection of light rays; a real image can be projected on screen.

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Seeing Colors

Why do we see colors?

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16-3-12 Seeing Colors

The colors that you perceive depend on the wavelengths of visible light that reach your eyes.

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16-3-13 Seeing Colors

White light from the sun actually contains light from the visible wavelengths of the electromagnetic spectrum.

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16-3-14 Seeing Colors, continued

–additive primary colors: red, green, and blue•Mixing light of the three additive primary colors makes white light.

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16-3-15 Seeing Colors, continued–subtractive primary colors: yellow,

cyan, and magenta• If filters or pigments of all three colors are combined in equal proportions, all visible light is absorbed resulting in black which is the absence of color