Created for CVCA Physics By Dick Heckathorn 1 June 2K + 5 Ray Box Investigations For Reflection - Refraction and Total Internal Reflection Created for CVCA Physics By Dick Heckathorn 1 June 2K + 5

#1 #2 30o 30o 60o 60o #3 Rays 1-2-3

Conclusion The angles are measured from the normal. The angle of incidence equals the angle of reflection.

Reflection r N i

Conclusion The angles are measured from the normal. The angle of incidence equals the angle of refraction. The incident ray, reflected ray and the normal all lie in the same plane.

Repeat for other three occurrences Reflect ray of light from mirror as shown. Insert a pin (1) on reflected light ray. Locate reflection surface of mirror on line. Mark and draw the light rays on paper Draw a line across center of paper Insert pin into cardboard as shown. Extend reflected rays behind mirror Remove mirror The image is located where the rays cross. Draw a line from object to image How is this line oriented relative to mirror line? Repeat for rays 3 and 4. How does length of red and purple line compare? Insert pin (2) on ray and draw it. Draw normal lines and compare angle ‘i’ and ‘r’ Repeat for other three occurrences Reflect a 2nd ray from mirror as shown Image Mirror i r Pin 4 3 2 1

Conclusion The image is always as far behind the reflecting surface (mirror) as the object is in front. The line connecting the image and object is perpendicular to the reflecting surface (mirror).

Note angle ‘i’ equals angle ‘r’ Draw line from object to mirror Locate object. Light travels this path from object to pin Note angle ‘i’ equals angle ‘r’ Draw line from object to mirror Why know where the image is? Repeat for eye 2, 3, and 4 Draw line representing mirror. Connect eye (1) and image Then draw line from mirror to eye 1 Locate eye (1) Locate image Image Mirror surface r i Object Pin 3 1 2 4

Conclusion Locating the image allows one to predict the path light will travel from the object to some location.

I1,2 I1 Mirror (1) I2 Object Mirror (2)

Mirror (1) Mirror (2) I1,2 I2 I1 Object

Periscope I1 Object I1,2

Pepper Ghost Bottle of Water 90o Plexiglas Candle

Peppers Ghost

T29-1B

T29-1B

T29-1B

All rays parallel to P.A. reflect back through ‘F’ #19 V P.A. F f All rays parallel to P.A. reflect back through ‘F’

Parabolic Mirror #20

Not all rays parallel to P.A. reflect back through ‘F’ Circular Mirror P.A. Not all rays parallel to P.A. reflect back through ‘F’

Circular Mirror P.A.

Go to curved mirror PowerPoint. Click

N #4 i r Measure angle i and angle r. Both = 0o

N #5 300 i r 19.50 Calculate Measure angle i and angle r.

Measure angle i and angle r. #6 600 i r 35.30 Calculate Measure angle i and angle r.

1.50 is called the index of refraction (nP) of the plastic. Using for both angles, what value did you get? It should be near 1.50 1.50 is called the index of refraction (nP) of the plastic.

Test your drawing with a light ray. Calculate the angle of refraction. Quiz N 750 40.10 Test your drawing with a light ray. Calculate the angle of refraction. Draw the refracted ray. Draw an incident ray of 75o.

N #7

N Use light ray to check. Draw the refracted ray Bent away/toward normal? Calculate angle of refraction 30.90 30.90 200 #8

It tells us which way the refracted ray bends. n1 sin θ1 = n2 sin θ2 It tells us which way the refracted ray bends. Does it all!!! What does it do? How? The bigger ‘n’ has the smaller ‘sin θ’ and thus the smaller ‘θ’ (angle).

Use light ray to check. Calculate angle of refraction Draw the refracted ray Bent away/toward normal? N 74.60 74.60 400 #9

N Calculate angle of refraction Now what do we do? Bent away/toward normal? Use light ray to check. Tilt!! 600 600 #10

N What happens here? 750 #11 750

N

Demonstrations T.I.R. Plastic T.I.R. Water T.I.R. Glass Tube Ball in/out of Water Mugs

Demo – Aquarium Balls Aquarium Balls Air Water

Calculate angle of refraction Which way is ray bent? 300 #12 Calculate angle of refraction Which way is ray bent? Draw the refracted ray. n=1.50 19.50 Draw the refracted ray. Check with ray box. Calculate angle of refraction Which way is ray bent? 300

Calculate angle of refraction #13 600 600 00 Calculate angle of refraction Calculate angle of refraction n=1.50

Calculate angle of refraction Calculate angle of refraction 18.20 11.80 280 17.80 #15 11.80 18.20 280 17.80 #14 n=1.50 Calculate angle of refraction Calculate angle of refraction Calculate angle of refraction Calculate angle of refraction

#18

That’s All Folks!! No 16-17