refraction experiment

The laws of Refraction are:

1. A ray of light that passes through a surface into a denser medium (such as from air to glass) is refracted toward the normal line. A ray that passes through a surface to a less dense medium, (such as from glass to air), is refracted away from the normal line.
2. The incident and refracted rays are in the same plane.
3. The ratio of the sine of the angle of incidence to the sine of the angle or refraction is a constant, called the relative index of refraction, equal to the ratio of the indices of refraction for the two media. This is known as "Snell's Law".

Where (n) is the relative index of refraction.

4. A ray emerging from a parallel sided block is parallel to the ray entering, but is displaced sideways.
5. A ray raveling along the normal is not refracted.

• The absolute refractive index is the ratio compared with the refractive index of a vacuum.  (n for a vacuum = 1.000;)
• The relative refractive index is the ratio of the absolute refractive index of one material compared to that of another, for example from water to glass.

Therefore in this whole experiment we would be calculating the relative refractive index as we are comparing water and glass.

This table shows us the refractive indices of different mediums:

Apparatus:

• Glass block
• White sheet of paper
• Thumb pins
• Laser
• Protractor
• Pencil
• Eraser
• Ruler

Fair test:

• Make sure that the glass block is aligned the right way and that it is kept constant so that you get the accurate angles of refraction.
• Make sure that angle of incidence is measured rightly and that the incident ray is drawn in the right manner.
• Make sure that the laser shone correctly over the line drawn for the incident ray, so that you get an accurate refracted ray.
• Make sure that the refracted ray is drawn accurately so that you get an accurate refracted ray. Make sure that the glass block is not displaced so that errors are reduced.

Safe test:

• You should make sure that the laser shone in the right manner over the incident ray drawn.
• Make sure that the reflected ray of the laser is extended so that when measuring the angles there will be lesser anomalies.

DATA COLLECTION:

Table 1:

Table 2:

ANALYSIS:

By looking at Table 1 and 2 we can easily see the angle of incidence, angle of refraction and the angle of emergence. We see that the angle of incidence and the angle of emergence are equal in almost all cases, and if not they are not they are almost equal. The maximum error is of 2° in one case, whereas on an average the results have been accurate. There could be many errors which could have resulted in some readings not being right. The glass block could have not been placed the right way. The normal line could have not been drawn accurately or the emergent rays could have been drawn inaccurately. The laser beams are sometimes too thick and therefore this could have resulted in anomaly.

The refractive index of glass before was said to be 1.5 on an average. Taking that into consideration, we can see that the refractive index of glass is proven to be right as they are all almost 1.5. But only 40° and 60° of angle of incidence have exceeded 1.5 whereas the other degrees are lesser than 1.5 but above 1.4. The average of the refractive indices is 1.49, which tells us that on an average the refractive index of glass was proven right.

CONCLUSION:

Therefore by looking at the table we can conclude and say that the angle of incidence is equal to the angle of emergence. By looking at the drawings we can say that the incident ray is parallel to the emergent ray. Moreover the refractive index of glass is proven to be 1.5 on an average. Finally we can say that the rays lie on the same plane.