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refraction experiment

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Aim: To study the phenomenon of refraction of light by using a glass block.

Theory: Light is one of the most fundamental energy forms and an understanding of several of its properties is essential to any understanding of science. In this investigation we would be seeing the different phenomenon of refraction of light.Refraction is a change in the direction of radiation that occurs when it crosses the interface between two media in which the radiation travels with different speeds. The radiation undergoes a change in speed, in wavelength, and in direction. These are a few common terms in relation to refraction of light:

  • Reflection: the process by which radiation that strikes a surface separating two media of different densities is in part or in whole turned back into the medium from which it originated. The radiation rebounds from a barrier in its path without a change in speed.
  • Normal line: A line perpendicular to the surface at the point where a ray of light strikes.
  • Incident Ray: A ray which impinges upon a surface.
  • Refracted Ray: a ray that has changed direction after crossing from one media to another, in which the speed is different.
  • Emergent ray: the light ray leaving a medium in contrast to the entering or incident ray.
  • Angle of incidence: the angle between the incident ray and a normal.
  • Angle of refraction: the angle between the refracted ray and the normal line.
  • Index of refraction: the ratio of the speed of light in a vacuum (c) to the speed of light in a different medium (v).
...read more.


This table shows us the refractive indices of different mediums:


Refractive Index














  • 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.
...read more.


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.


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.

...read more.

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Here's what a teacher thought of this essay

4 star(s)

This is a well structured and well written report.
1. The sources of information need to be referenced.
2. The conclusion needs to explain the pattern.
3. The report needs to have an evaluation.

Marked by teacher Luke Smithen 13/08/2013

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