Download 4.Bending Light PhET

Name:
Bending Light and Geometric Optics PhETs
Google the phrase, “Bending Light PhET” and click on the first link.
Click the “Download Now!” button.
In the last unit, you learned that reflection occurs when light bounces off of a surface.
Refraction occurs when light changes direction (bends) when entering a new medium.
The laser is pointing towards water.
Push the red button on the laser to
turn it on. You will notice that some
light reflects off the surface of the
water, and some light refracts as it
enters the water.
1. Label each ray as “reflected” or
“refracted” in the picture to the right.
Place a protractor like shown in the
picture.
2. Shoot the laser at the following angles and record the reflected and refracted angles:
Incoming Angle
15˚
30˚
45˚
60˚
75˚
Reflected Angle Refracted Angle
3. How does the incoming ray angle always compare to the reflected ray angle? (Is one bigger
than the other? Which one?)
4. How does the incoming ray angle compare to the refracted ray angle? (Is one bigger than the
other? Which one?)
Name:
5. Change the bottom type of material from water to something else. Does this affect the angle
of reflection?
6. SLOWLY change the bottom type of material from water to glass. What does this do to the
angle of refraction?
Make sure your materials are “air” on top and “water” on the bottom again, before starting this
next part.
7. What happens to the refracted ray’s angle when you make the laser’s angle equal to zero?
8. Change the “Laser View” to “Wave.” Try changing the laser’s angle again.
What happens to the wavelength of a wave when it refracts?
Prism Break
Click on the “Prism Break” tab.
Under the spectrum, click on “White
Light.”
9. What happens when light goes through
prisms of different shapes? Experiment
with at least two prisms, and draw two
pictures below to explain.
Name:
10. How do you make a rainbow with a prism? (What kind of prism do you need? Does any angle
work?)
11. Click on “multiple rays.” On the picture below, draw
how light travels through the convex lens.
A convex lens acts the same as a ____________ mirror.
12. On the picture below, draw how light travels through the concave lens.
A concave lens acts the same as a ____________ mirror.
Go back onto the internet page. Google “Refraction.”
13. Find 5 different pictures of refraction in the REAL WORLD. Paste them into a WORD
document. Ask me to come over and show it to me.
Teacher Signature: ______________
Name:
Google the phrase, “Geometric Optics PhET” and click on the first link. Click the green “Run
Now!” button.
14. Click on principal rays. Move the object around.
Notice the direction, size, and location of the image.
What type of mirror is this convex lens similar to?
15. Look at the light rays as you move the object around. Regardless where you place the
object, how are the light rays drawn through the convex lens to locate the image? (the X’s mark
the focal points)
16. Use a light ray diagram to locate the image.
F
F
17. Change the curvature radius. Does this affect the focal point of the lens? ___________
How does it affect how light travels through the lens?
18. Change the refractive index. A lens with a larger refractive index will bend light (more or
less).
19. How would light travel through a material with a refractive index of zero?