Light Lab – Cycle I - 20 points

Instructions:

You will be asked to perform a variety of different experiments with Maglights. Your job is to draw, describe and explain the outcome of these experiments. Be sure to explain which light produces which “dot” or “shadow”. Be sure to explain the relative focus, brightness (amplitude) and sizes of “dots” and/or “shadows” on the screen. Basically, you should have a short sentence or two under your drawings which explain these outcomes. It is SO IMPORTANT that you determine which light makes which “dot” or “shadow”. Cover up your lights one at a time to help you figure this out.

Example: Put two maglights in the holder and place a 5 cm² card 1/2 way between the maglight and the screen.

Draw a side view and a front view. Sometimes you can draw one side view and 3 front views. Look at questions 1-3 and see how they are so similar that you can do this.

Maglight experiments:

Using the completely opaque 5cm² card (3 points)

1. Put one maglight in the holder and place a 5 cm² card 1/2 way between the maglight and the screen.

2. Put one maglight in the holder and place a 5 cm² card closer to the maglight than the screen.

3. Put one maglight in the holder and place a 5 cm² card closer to the the screen than the maglight.

4. Put two maglights in the holder and place a 5 cm² card 1/2 way between the maglight and the screen.

5. Put two maglights in the holder and place a 5 cm² card closer to the maglight than the screen.

6. Put two maglights in the holder and place a 5 cm² card closer to the screen than the maglight.

Using the ONE PIN HOLED card (3 points) – drawing = 2 points, description = 1 pt.

7. Put one maglight in the holder and place the one hole card 1/2 way between the maglight and the screen.

8. Put one maglight in the holder and place the one hole card closer to the maglight than the screen.

9. Put one maglight in the holder and place the one hole card closer to the the screen than the maglight.

10. Put one maglight in the holder and place the one hole card so that a single pin-point of light shines on the screen. Show and explain what happens when you move the maglight to a hole in the holder one notch LOWER than it is in currently (do not move the card!) Does the pin-point of light move up? Move down? Or stay in the same location? Make sure you draw a side view of the maglight and holder for this one!

11. Put two maglights in the holder and place the one hole card 1/2 way between the maglight and the screen.

12. Put two maglights in the holder and place the one hole card closer to the maglight than the screen.

13. Put two maglights in the holder and the one hole card closer to the screen than the maglight.

14. Put two maglights in the holder and place the one hole card so that two dots of light shine on the screen. Which light is making which dot?

Using the TWO PIN HOLED card (3 points) – drawing = 2 points, description = 1 pt.

15. Put one maglight in the holder and place the two holed card 1/2 way between the mag. and the screen.

16. Put one maglight in the holder and place the two holed card closer to the maglight than the screen.

17. Put one maglight in the holder and place the two holed card closer to the screen than the maglight.

18. Put one maglight in the holder and place the two holed card so that two points of light shine on the screen. Show and explain what happens when you move the maglight to a hole in the holder one notch LOWER than it is in currently (do not move the card!) Does the pin-points of light move up? Move down? Or stay in the same location? Make sure you draw a side view of the maglight and holder for this one!

19. Put two maglights in the holder and place the two holed card 1/2 way between the mag. and the screen.

20. Put two maglights in the holder and place the two holed card closer to the maglight than the screen.

21. Put two maglights in the holder and the two holed card closer to the screen than the maglight.

22. Put two maglights in the holder and place the two holed card so that FOUR points of light shine on the screen. Show and explain what happens when you move the maglights to a more separate notches in the holder (do not move the card!) Does the pin-points of light move up? Move down? Or stay in the same location? Make sure you draw a side view of the maglight and holder for this one!

23. Put two maglights in the holder and place the two holed card so that FOUR points of light shine on the screen and then rotate the card 90 degrees. What happens to the dots of light and explain why this occurs

General Questions after completing these experiments:

24. Look at the drawing below. Using straight lines, show how the light rays go from the maglights to the screen. (2 points)

25. When the maglight was CLOSER to the one-holed card than the card was to the screen, how did the image size of the bulb appear on the screen? The same size as the actual bulb? Larger than the actual bulb? Smaller than the actual bulb? (1 point)

26. When the maglight was FURTHER from the one-holed card than the card was from the screen, how did the image size of the bulb appear on the screen? The same size as the actual bulb? Larger than the actual bulb? Smaller than the actual bulb? (1 point)

27. When the maglight was EQUAL DISTANT from the one-holed card than the card was from the screen, how did the image size of the bulb appear on the screen? The same size as the actual bulb? Larger than the actual bulb? Smaller than the actual bulb? (1 point)

28. Use a ruler and measure carefully for this question: Can you come up with an equation which relates the distances between the card and the light source, the card and the screen and the sizes of the source bulb and the image on the screen? Look at drawing below for help (2 points)

29. Predict what you would see on the screen if you had the following set-up. (once you have made your prediction, show it to Mr. Young and get a candle and try it out!) (2 points)

30. What do you think will happen (in question #29) if the hole in the card is LARGER than a pin-hole. Say, ONE inch in diameter. Make a card with a ONE inch diameter hole in it and try it out. Why do you think this happened? (2 points)