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Sir Isaac Newton- 1672

It was a wild ride through time as I landed in England near Sir Isaac Newton’s home. Fortunately, he was reading in his house. I introduced myself as a traveller from another part in England that came to visit him to learn more about optics. I couldn’t reveal myself as a time traveller because complications could arise. Newton was very friendly and led me to his workspace.

Newton said that I had come at just about the right time to learn about optics, light and colour as he was currently investigating this topic. Although his equipment was very basic and low tech, he managed to make many discoveries. I was very impressed with his work and Newton even showed me an experiment.

The experiment Newton showed me was one regarding refraction of a prism. Newton proved that white light is divided into a spectrum of colours when it goes through a glass prism. In his time, people thought that the glass prism gave colours to the white light as the light passed through. Newton proved this to be false by placing a screen in the path of a coloured light so that only one colour could pass through. He placed a prism in front of the coloured light. When the light did not turn into a spectrum of colours, Newton had proved that it wasn’t the prism that changed the colour of the light. Hence, he concluded that white light itself is made up of a mixture if seven colours itself.

Newton explained his theory to me and showed me how he proved his theory that white light itself was made up of colours. I was lucky enough to see this experiment with my own eyes and it inspired me to do better in the great topic of optics and magnetism.

I stayed for a few weeks with Newton as he told me everything he knew about optics. He explained to me about his theories and I was able to guide him in the right direction with a few theories as my knowledge on light surpassed his as I came from the future where all his theories were either proven true or false. Unfortunately, I had to leave to visit another scientist.

My next stop: Alhazen in the year 1030!

 

Title:

Dispersion of White Light

Background Information:

White light is composed of different colours which can be dispersed by refraction using a glass prism. This splitting of white light is called dispersion. White light disperses because different colours of light have different wavelengths; therefore, different colours of light bend towards the normal through different angles when entering the prism and when leaving the prism. For example, the colour red hardly refracts at all whereas the colour violet refracts the most; thus, they are at opposite ends of the visible colour spectrum.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Aim:

To split white light into seven different colours using a glass prism then converging the colours back together using an inverted glass prism.

Hypothesis:

I believe that the white light will split into a spectrum of colours due to the different wavelengths of the colours. When an extra prism is added to the colours, all the different colours should converge back into white light as the inverted glass prism should combine the colours.

Safety:

As a safety requirement, lab coats must be worn and a teacher must be present during the conduction of the experiment. The light box should also be kept away from water in case of an electrical shock.

Variables:

Independent variable: Placement and the degree/angle you turn the prism

Dependent variable: The colour spectrum that comes out from the prism

Controlled variable: the light emits from the same place and only the prism is turned

Apparatus/Materials:

  • Light box
  • Power outlet
  • Power box
  • 2 glass prisms

Method:

  1. Create a single beam from your light source
  2. Place the prism in the path of the beam of light
  3. Turn the prism in different angles to best achieve a colour spectrum which comes out from the other side
  4. Place another prism in the path of the colour spectrum to make a white light again

Diagram:

Diagram

Results:

Dispersion of White Light Experiment

As expected, the first prism split the white light into a spectrum of colours (red, orange, yellow, green, blue, indigo and violet). When an inverted prism was placed on the path of the colour spectrum, the resulting light that came out was a white beam of light.

Observations:

When the light entered the prisms, it would refract but not perfectly. Some of the light had total internal reflection so that the light kept coming out from different sides of the prism; therefore, it was complicated to find an angle where the prism best displayed the colours of the colour spectrum.

Discussion:

Although there is not much data regarding this experiment, the light is split into colours by a prism then converges again by an inverted prism. This can be considered a pattern as the first prism will always split the light and the second inverted prism will mix it together again to form a white light.

Evaluation:

(Reliability of data, strengths/improvements, validity of method)

Unfortunately, the results that are gathered from this experiment are general as there is no specific mathematical concept used. This test proved a concept more than experimenting on a particular idea/concept. One of the strengths was to keep the results as reliable as we can, the same equipment was used for the experiment. However, there is still a large margin for error as different prisms may have slightly different results so this experiment isn’t valid. One improvement that could be made is to have a specific prism that people have to use when doing this experiment so the results are as similar as possible.

The method is quite valid as it allows us to gather all the necessary data to form a hypothesis regarding this experiment. One improvement that could be made is to measure at what angle the prisms need to be placed to create a colour spectrum which comes back together to form white light.

Conclusion:

In conclusion, the hypothesis was supported as the first prism did split the white light and the second inverted prism brought the light back together.


Posted by on October 17, 2011 at 11:38 am | Comments & Trackbacks (0)




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