Aim
To study the refraction of light through a glass slab and understand how light bends when passing through different media. This experiment helps verify the laws of refraction, including the concept of the refractive index.
Materials Required
- Glass slab (preferably rectangular)
- Laser pointer or beam of light
- Protractor (for measuring angles accurately)
- Paper (for tracing the rays and slab outline)
- Pencil (for marking angles)
Image Reference
Procedure
- Place the glass slab on a sheet of paper and trace its outline to mark its position.
- Shine a laser pointer or beam of light at the surface of the glass slab at a specific angle, called the angle of incidence.
- Trace the incident ray as it strikes the glass slab. Upon passing through the slab, trace the refracted ray, which bends towards the normal due to the change in medium.
- As the light exits the slab, trace the emergent ray. The emergent ray will bend away from the normal, and its path will be parallel to the incident ray.
- Use a protractor to measure the angle of incidence, the angle of refraction inside the slab, and the angle of emergence as the light exits the slab.
- Repeat the process for different angles of incidence to observe how the angle of refraction changes with the incident angle.
Observation
It is observed that the light ray bends towards the normal when it enters the glass slab and bends away from the normal when it exits the slab. This is due to the difference in the refractive indices of air and glass. The angle of incidence is equal to the angle of emergence, confirming the law of refraction.
Precautions
- Ensure that the glass slab is placed flat on the paper to avoid any angle errors.
- Use a sharp pencil for accurate tracing of the rays.
- Ensure that the laser pointer is steady and directed at the slab at a constant angle for consistent results.
- Make sure the protractor is aligned properly to measure the angles of incidence, refraction, and emergence accurately.
Conclusion
This experiment verifies the laws of refraction, where the angle of incidence and the angle of refraction are related by the refractive index of the medium. The bending of light when passing through a glass slab confirms the behavior predicted by Snell's law of refraction.