PROBLEM: To calculate the index of refraction for water.
MATERIALS: Large beaker ( two liter plastic bottle with 10 centimeters cut of the top ) water, a coin, metric ruler.
PROCEDURE AND OBSERVATION:
1. ( if using glass) Slide coin gently into the beaker; Add water until it is about 5 cm deep.
2. Looking directly over the top of the beaker, observe the coin. Notice that the coin looks larger and does not appear to be resting on the bottom of the beaker.
3. You know the actual depth of the water is 5 cm . Now you have to find the apparent depth of the coin.
4. To find the apparent depth; hold the ruler next to the beaker and place the tip of your pen against the side of the beaker. Looking over the beaker, try to observe the pen and the coin at the same time. And move the pen up and down until you feel that the coin and the pen are the same distance above the bottom. Record the apparent height of the coin.
5. Now subtract your apparent height of the coin from 5 cm to get your apparent depth. To find the index of refraction use the following formula;
| ACTUAL DEPTH OF COIN | |
| INDEX OF REFRACTION = | --------------------------------------------- |
| APPARENT DEPTH OF COIN |
6. Now, repeat above the steps and complete the table below.
Actual depth of coin |
Apparent depth of coin |
Index of refraction of water |
5 cm |
||
10 cm |
||
15 cm |
||
18 cm |
QUESTIONS:
1. What is your average for the index of refraction for water ?
2. What does the index of refraction indicate ?
3. Would hot and cold water have the same index of refraction ? Explain.
4. Cold water has a greater density, how would this effect the index of refraction ?
5. Define diverging lens.
6. Define converging lens
7. Describe the shape of a convex lens.
8. Describe the shape of concave lens.
9. What is the difference between an object and an image ?
10. How could you increase the density of glass ?
11. How could you increase the index of refraction for a transparent liquid ?
12. What is total internal reflection ?
13. At what angle will total internal reflection occur for water ?
14. Name a glass object that makes use of total internal reflection.