Chapter Name: Refraction of Light At Plane Surfaces
Activity Name: Straight line view in Refraction of Light At Plane Surfaces
This experiment demonstrates the phenomenon of refraction of light using a shallow vessel with opaque walls, a coin, and water. By observing the position of the coin from different distances, and with and without water, the experiment explores how refraction allows the coin to become visible when the vessel is filled with water.
- Shallow vessel with opaque walls (e.g., mug, tin, or pan)
Step by Step Procedure:
- Place the coin at the bottom of the shallow vessel.
- Move away from the vessel until you cannot see the coin (Figure 1b).
- Stand in that position and ask your friend to fill the vessel with water.
- Observe that when the vessel is filled with water, the coin comes back into view (Figure 1c).
- When the vessel is empty, and you are standing at a certain distance, the coin is not visible.
- After filling the vessel with water and observing from the same position, the coin becomes visible.
- Use a shallow vessel with opaque walls to ensure that light doesn’t pass through the sides.
- Keep the coin clean and visible at the bottom of the vessel.
Lesson Learnt from Experiment:
The experiment demonstrates the concept of refraction, where light changes its direction as it passes from one medium (air) to another medium (water) with a different optical density.
When light travels from air to water, it bends towards the normal (an imaginary line perpendicular to the water surface). As a result, the light rays from the coin that were previously not reaching your eye are now bent towards your eye, allowing you to see the coin when the vessel is filled with water.