Ray Box Investigations For Reflection - Refraction and Total Internal Reflection

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Ray Box Investigations For Reflection - Refraction and Total Internal Reflection. Created for CVCA Physics By Dick Heckathorn 1 June 2K + 5. #1. #2. 30 o. 30 o. 60 o. 60 o. #3. Rays 1-2-3. Conclusion. The angles are measured from the normal.

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### Ray Box InvestigationsForReflection - RefractionandTotal 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.

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.

Extend reflected rays behind mirror

Locate reflection surface of mirror on line.

Reflect ray of light from mirror as shown.

Insert a pin (1) on reflected light ray.

Draw a line from object to image

Mark and draw the light rays on paper

Insert pin into cardboard as shown.

Remove mirror

The image is located where the rays cross.

Draw a line across center of paper

Repeat for rays 3 and 4.

Insert pin (2) on ray and draw it.

Reflect a 2nd ray from mirror as shown

Repeat for other three occurrences

How is this line oriented relative to mirror line?

How does length of red and purple line compare?

Draw normal lines and compare angle ‘i’ and ‘r’

Image

Mirror

i

r

Pin

2

4

3

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).

Locate object.

Repeat for eye 2, 3, and 4

Draw line representing mirror.

Connect eye (1) and image

Draw line from object to mirror

Light travels this path from object to pin

Note angle ‘i’ equals angle ‘r’

Then draw line from mirror to eye 1

Locate image

Locate eye (1)

Why know where the image is?

Image

Mirror surface

r

i

Object

Pin

3

1

4

2

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

#19

V

P.A.

F

f

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’

N

#4

i

r

Measure angle i and angle r.

Both = 0o

#5

N

300

i

r

19.50

Calculate

Measure angle i and angle r.

N

#6

600

i

r

35.30

Calculate

Measure angle i and angle r.

for both angles,

Using

what value did you get?

It should be near 1.50

1.50 is called the index of refraction (nP) of the plastic.

N

Quiz

750

40.10

Calculate the angle of refraction.

Draw an incident ray of 75o.

Test your drawing with a light ray.

Draw the refracted ray.

N

#7

N

Calculate angle of refraction

Use light ray to check.

Bent away/toward normal?

Draw the refracted ray

30.90

30.90

200

#8

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).

N

Bent away/toward normal?

Calculate angle of refraction

Draw the refracted ray

Use light ray to check.

74.60

74.60

400

#9

N

Bent away/toward normal?

Use light ray to check.

Now what do we do?

Calculate angle of refraction

Tilt!!

600

600

#10

N

What happens here?

750

750

#11

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

300

#12

Draw the refracted ray.

Calculate angle of refraction

Which way is ray bent?

n=1.50

19.50

Check with ray box.

Calculate angle of refraction

Which way is ray bent?

Draw the refracted ray.

300

#13

600

600

00

Calculate angle of refraction

Calculate angle of refraction

n=1.50

11.80

18.20

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