A student has to trace the path of a ray of light through a glass prism. List four precautions he should observe for better results.

The four precautions which a student should observe while tracing the path of a ray of light through a glass prism are as follows:

1. Make sure the prism taken is polished and not broken.

2. Make sure to look at the image through the proper eye level through the prism.

3. A sharp pencil should be used for drawing the boundary of the glass prism so that sharp lines can be drawn to observe the proper results.

4. The angle of incidence ideally should be $45^o$ for a better outcome.

Explanation

In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray bends at an angle to the direction of the incident ray. This happens because the light ray gets refracted two times at different angles. So, the emergent rays bend at an angle towards the direction of the incident ray.

It can be shown with the help of the following diagram: