The fact that light bends when it moves from one material to another is a strong indication of its wave properties. Light will travel in a straight line as long as it is moving through one medium. However, when it is leaving one material and entering another at an angle, it will bend. If a ray of light travels from a less dense medium to a more dense medium (traveling from air to water), it will bend toward the normal (perpendicular line to the boundary of the two materials). If it is leaving the denser material into the less dense material, it will bend the other way, away from the normal.
To determine the specific relationship between the angle of incidence and the angle of reflection to see and quantify the refraction of light.
- Clear all surfaces before beginning work.
- Read through the whole experiment before you start.
- Identify hazardous procedures and anticipate dangers.
Apparatus and Materials:
- Blu tack
- Bowl filled with water
1. Place the blu tack in the middle of the coin.
2. Position the blu tacked coin in the center of your pot so that it is secured down (will not move when you pour water into the pot). Put some water in a cup to pour into your bowl.
3. Move backwards away from the bowl until you cannot see the coin in the bowl.
4. Very slowly pour some water into the bowl until the coin starts to appear before your eyes.
5. Pour a bit more water, very slowly, and continue watching as the coin reveals itself. Watch the bowl from where you are standing.
- – At first, the coin is hidden from sight behind the rim of the bowl.
- – As the water is poured in, more and more of the coin becomes visible until the whole coin can be seen, almost as if it is floating upwards.
- – Then finally, no coin.at first the coin is hidden from your site behind the rim of the bowl.
- – Suddenly, the coin appears.
The coin disappears only when you view it at a range of angles. The film strip is used to ensure that the students do observe what you expect them to see. Video strip are useful also when some experiments are hard to perform in the school laboratory, either too dangerous or apparatus being unavailable. The simulating model allows students to explore on how the light rays go through the beaker of water under widely different conditions.
As the water is poured into the bowl, the light is refracted. In doing so the image of the coin is moved up so that your eyes can see it (check out the diagram below). So what you are actually seeing is the image of the coin, and not the actual coin!