Chapter Name: Refraction of Light At Plane Surfaces
Activity Name: Behaviour of light ray travels from denser to rarer in Refraction of Light At Plane Surfaces
This experiment involves using a metal disk with marked angles and two straws immersed in water. By adjusting the straws, students will observe how light rays bend away from the normal when traveling from a denser medium (water) to a rarer medium (air).
- Metal disk, protractor, transparent vessel, water, two straws.
Step by Step Procedure:
- Mark angles on the metal disk using a protractor.
- Arrange two straws at the center of the disk, allowing them to rotate freely.
- Adjust one straw to make an angle of 100 degrees.
- Immerse half of the disk vertically in water.
- Verify that the straw at 100 degrees is inside the water.
- Look from the top of the vessel and adjust the other straw outside the water until both straws appear in a single straight line.
- Take the disk out of the water and observe the two straws; they will not be in a straight line.
- Measure the angle between the normal and the second straw and note the value in a table.
- Repeat the procedure for various angles and find the corresponding angles of refraction, noting them in the table.
- Use the data to calculate the refractive index of water.
- Light rays appear to be in a straight line when viewed from the top due to refraction.
- Avoid taking up this activity for angles of incidence greater than 48 degrees.
- Handle the metal disk and straws carefully to avoid any damage.
Lesson Learnt from Experiment:
When light travels from a denser medium (e.g., water) to a rarer medium (e.g., air), it bends away from the normal, and the angle of refraction (r) is greater than the angle of incidence (i).