Welcome back Minions!

Warm up on the board!!!

Thought to start out…

• If you know the answer… keep it to yourself. Don’t spoil it for others.

What color is a mirror?

Today…

• Manipulation of light!– Reflection– Refraction– Diffraction– Absorption

• How the human eye sees color!

Eye See You!

Ever see cats’ eyes in the dark when light shines on them?

Cats have a special layer of cells in the back of their eyes that reflect light.

Reflection

• Reflection– When a wave hits an

object it cannot pass through, it bounces back.

• Law of Reflection– Angle of incidence

equals the angle of reflection

Don’t believe your eyes!!!

• Ever notice…

• ??????

Refraction

• Refraction– The bending of waves

as they enter a new medium at an angle.

Bending, not breaking…

• Ever notice…

• Wha???

Diffraction

• Diffraction– Slight bending of light

as it passes around the edge of an object.

How we see color…

• What is color?

• How do we perceive color?

Color

• Color– The property possessed by an object of producing

different sensations on the eye as a result of the way it reflects or emits light.

But how do we see color?

• Absorption– The way in which the energy of a photon is taken

up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat.

Ok… but how do we see color?

If a light wave of a given frequency strikes a material with electrons having the same vibrational frequencies, then those electrons will absorb the energy of the light wave and transform it into vibrational motion.

During its vibration, the electrons interact with neighboring atoms in such a manner as to convert its vibrational energy into thermal energy.

Subsequently, the light wave with that given frequency is absorbed by the object, never again to be released in the form of light.

So… what is the answer?

You see the discarded (reflected) leftover.

Oh yeah… the mirror question…

Green