OPTICS 02

Find Monday's Recorded Zoom Session HERE

Audio only is HERE

 

 

OPENING QUESTIONS: Sketch an example of "retroreflection" using either a circle or a square (that *should* make sense after yesterday's class)

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LEARNING TARGET: I will be able to use the Law of Reflection to calculate the angle in which a light way is reflected from one or more mirrors after today's class.

 

WORDS O' THE DAY:

    • Reflection ("Light waves bouncing off an object")
    • Emission ("Light is given off by an object")
    • Absorption ("Some wavelengths of light are absorbed by an object")
    • Angle of Incidence ("The angle a light ray takes as it moves toward a reflecting surface")
    • Angle of Reflection ("The angle a light ray takes as it moves away from a reflecting object")
    • Retroreflection ("incident light waves are 'double bounced' back to the observer, regardless of the angle of incidence")

WORK O' THE DAY:

Discussion of the Law of Reflection

Perhaps the most basic of all the laws of optics is the Law of Reflection:

"The angle of incidence equals the angle of reflection"

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Notice that the angles are each measured in reference to the NORMAL (perpindicular) line

The law of reflection can and often is written mathematically as follows:

θ1 = θ1'

and pronounced as "theta one = theta one prime" to emphasize the sameness of the angles.

To make life a bit easier for us I will often replace that with

θi = θr

to emphasize the angle of incidence = the angle of reflection

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Retroreflection is SUPER helpful in our day-to-day life.

It acts so that any light falling on the first surface is "double bounced" off of a second surface and returned back to the light source... REGARDLESS of angle of incidence.

Retroreflection is done using either a cubic or spherical surface...

Now please (*GASP*) bust out your forbidden electronic devices and find yourself a protractor app! We've had good luck with the Keuwlsoft App (Android), PhotoProtractor (Apple)

Moving Right along-- please download this light ray practice

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