• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Investigation to find the change in the speed of light through perspex.

Extracts from this document...


Investigation to find the change in the speed of light through perspex Aim I intend to investigate the change in the speed of light in perspex. I intend to do this by passing a narrow ray of light through a D-block of Perspex, by using the same concepts and ideas as Snell's Law. Background Information Light is an electromagnetic wave. The speed of light depends on the medium through which it propagates: it goes fastest in vacuum, almost as fast in air but considerably slower in glass. The speed of light in a vacuum has been given its own symbol: c. The speed of light in any other material is denoted with v. The ratio of the two is known as the refractive index with the symbol n. When light goes from one medium to another, it doesn't only change its speed. Part of the incident light is reflected, and the remainder is transmitted. The transmitted light is generally also deviated or refracted. It was found experimentally by Descartes and by Snell, some 400 years ago that: � The incident, reflected and refracted ray all lie in the same plane � The angles of incidence ? ...read more.


Prediction information It is known that the speed of light in air is 300,000,000 m/s, so firstly work out what sine I over sine r is and you multiply 300,000,000 by what ever you work out sine I over sine r to be. E.g. if the refractive index = 0.65 you would do 300,000,000 x 0.60 = 180,000,000. If the refractive index was actually 0.65 then the speed of light in perspex would be 180,000,000 m/s. Prediction Graph Results (first set of results) No. i (�) r(�) Sin i(�) Sin r(�) Sin i/Sin r 1 5 7.5 0.087 0.13 0.67 2 10 15 0.17 0.25 0.67 3 15 24 0.25 0.40 0.64 4 20 31 0.34 0.51 0.66 5 25 38 0.42 0.61 0.69 6 30 45 0.5 0.70 0.71 7 35 57.5 0.57 0.84 0.68 8 40 69 0.64 0.93 0.69 Average 0.68 No. i (�) r(�) Sin i(�) Sin r(�) Sin i/Sin r 1 5 7.3 0.087 0.12 0.75 2 10 16 0.17 0.27 0.63 3 15 21 0.25 0.35 0.71 4 20 31 0.34 0.52 0.65 5 25 41 0.42 0.66 0.63 6 30 47 0.5 0.73 0.68 7 35 54 0.57 0.80 0.71 8 40 71 0.64 0.95 0.67 Average 0.68 From the table I am able to calculate the speed of the light in perspex. ...read more.


Another factor may be using the collimator to produce the light beam. The collimator had a small slit in to allow light to travel through; I feel that the slit used in the experiment could have been a bit narrower to have produced a much more slender ray so we could have drawn it a bit more accurately. The D-block was occasionally knocked and moved slightly off the point it was supposed to be on. This meant that we had to place it back a number of times. This unfortunately may have resulted in readings being taken with the d-block at a different position than the previous readings. The results would therefore be inaccurate. If implemented these changes would provide a repeat experiment with a higher degree of accuracy. Further Experimentation I could also find out the speed of the various colours of light through perspex to gain a wider range of results. This would mean using a wider slit on the collimator to get a wider scatter of the 7 colours, and so that each is distinguishable by some margin. Once the data has been collected, averaged, graphed and analysed hopefully it would be possible to get an answer such as mine, but increasingly accurate. This would provide a figure that would be most definitely closer to the actual speed of light through perspex. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our GCSE Waves section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Here's what a teacher thought of this essay

4 star(s)

This is a well structured and well written result.
1. The sources of information need to be referenced.
2. The word 'proved' is used many times and needs to be removed.
3. The conclusion needs to explain the results using researched information.

Marked by teacher Luke Smithen 13/08/2013

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related GCSE Waves essays

  1. Marked by a teacher

    An investigation into the factors affecting the frequency of a standing wave

    4 star(s)

    Using the signal generator which will be connected to either end of the length of wire, different frequencies can be used to create standing waves down different lengths of wire. I will use different lengths of wire to see what frequency is needed to produce a clean standing wave, which

  2. Marked by a teacher

    refraction experiment

    4 star(s)

    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.

  1. Marked by a teacher

    Resonance of a Wine Glass

    3 star(s)

    I connected the oscilloscope to the power supply and adjusted the settings to my liking. I then attached the highly sensitive microphone to a jar of around the same height as the wine glass using selotape. Finally I selotaped the glass to the work area so as the distance between

  2. refractive index prac report

    Compare the results to other practicals that were conducted and compare views and data. The Results: It can be seen from the graph 'Sinr Vs Sini' the line of best fits' slop is Y=0.642x-0.0228.

  1. To investigate how the depth of the water will effect the speed of a ...

    the tray because a tray dropped from a greater height will mean a greater force on the wave which according to the equation: F = ma (Patrick Fullick's GCSE Physics)

  2. Investigating the speed of travelling waves in water.

    In order to measure 0.5cm of water accurately a setsquare can be used. The shorter side of the setsquare can be placed on the base of the inside of the tray, and the longer side will be used to measure the depth of the water.

  1. Focal length of Concave and Convex lens

    It is because we do not whether there are any other factors are affecting the result. Discussion Since the meter rules have their scale 1mm. So the error of our result should have about +- 0.05cm error. Secondly the result will be more accurate if we can minimize the distance

  2. Properties of waves

    Electromagnetic waves may be caused by vibrating particles d. In a mechanical wave, the particles in the medium also vibrate as the wave passes through the medium. VII. Vibrations involve transformations of energy i. refer to page 359 for the diagram and description for this section VIII.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work