• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
Page
  1. 1
    1
  2. 2
    2
  3. 3
    3
  4. 4
    4
  5. 5
    5
  6. 6
    6
  7. 7
    7
  8. 8
    8
  9. 9
    9

Find a relationship between the angles of incidence and the angles of refraction by obtaining a set of readings for the angles of incidence and refraction as a light ray passes from air into perspex.

Extracts from this document...

Introduction

Refraction of Light Aim: To find a relationship between the angles of incidence and the angles of refraction by obtaining a set of readings for the angles of incidence and refraction as a light ray passes from air into perspex. Introduction: Refraction is the bending of a wave when it enters a medium where it's speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media. The amount of bending depends on the indices of refraction of the two media and is described quantitatively by Snell's Law. (Refer to diagram below) The index of refraction is defined as the speed of light in vacuum divided by the speed of light in the medium. In this experiment, the index of refraction for the perspex is 1.50. Snell's Law relates the indices of refraction of the two media to the directions of propagation in terms of the angles to the normal. It refers to the relationship between the different angles of light as it passes from one transparent medium to another. When light passes from one transparent medium to another, it bends according to Snell's law which states: where: n1 is the refractive index of the medium the light is leaving, n2 is the refractive index of the medium the ...read more.

Middle

Difficulties encountered and how they were overcome: * Accuracy of angles: used a protractor to measure * Accuracy of refractive angles as the beam thickened as it passed through the perspex: measured and marked a point on the grid as closely as possible to the narrowest part of the light ray. * Ensuring that the light went through the centre of the perspex: repeated each angle 2-3 times to be sure of the results acquired * Keeping the perspex stable: one person held the perspex while another marked the points. Results: The results obtained were as accurate as possible, and covered a range of angles, from 0 degrees to 80 degrees and not above that, as the light ray would have been reflected. Also, the results obtained were narrowed to + or - each side of the result. Lastly, the results from three other students in the class were compared and then averaged to ensure accuracy. Angle of Incidence Angle of Refraction Average Sin Incidence Sin Refraction sin i/sin r 0 0 0 0 0 0 0 0 0 10 7 7 6 7 7 0.174 0.116 1.503 20 13 12 13 14 13 0.342 0.226 1.513 30 19 22 20 20.5 19 0.5 0.327 1.528 40 25 25 24 24.5 25 0.643 0.416 1.547 50 31 31 31 32 31 0.766 0.515 1.487 55 33 31.5 32 32.5 33 ...read more.

Conclusion

* The protractor, only measuring to an accuracy of 1 degree, which may cause the results to be slightly inaccurate. * Thick refractive light ray which may have cause a difference of almost 3 degrees. * The ray of light passing right through the middle of the perspex. Uncertainty of data and calculations: * Making precise, exact line of the light rays * Parallax error * Estimation of where to draw point Expected and derived relationships or physical values: * The expected result for the relationship between the incident angle and the refracted angle is a constant, 1.50 which is the relative index for the perspex. The derived results are quite accurate, due to the result being obtained and averaged out by comparing the results of three other people. However, the result can be further improved by using a grid that has the protractor printed on it. This would make it easier, to read the angle of both the incident and refracted rays. Conclusion: The investigation of the relationship between the incident angle and the refracted angle was a success. The absolute refractive index of perspex was proven to be 1.50, although there were slight differences in the results. Also, the investigation proved that Snell's law is correct and that when light passes through a medium that is denser, it bends (refraction). Also, the gradient, of any graph plotted for sin i over sin r for particular material, results in a constant, which is its relative index. ...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

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

    Investigation:To find the refractive index of cooking oil.

    4 star(s)

    These results may not be exact, but a rough guide, which will help to predict the refractive index for oil. I will use the following method for the pilot experiment. 1. Prepare the required apparatus 2. On the piece of paper place the empty plastic tray and draw round the base of the tray.

  2. Marked by a teacher

    Find the critical angle and refractive index for plastic using a graphical treatment for ...

    4 star(s)

    Fit the slit on the ray box allowing only a small ray of light through. 6. Then turn on the PSU. 7. Then shine the light on the interval and make sure it comes out of the centre of the straight side.

  1. Find out the speed of light through Perspex by passing a narrow ray of ...

    * Once we had completed the experiment we created a table of results that showed the angle of incidence, angle of refraction, the sine of both these angles and the sine of i over the sine of r. * But because we had a wide spread of figures we had to then average them.

  2. The aim of my experiment is to see what factors affect electromagnetism the most ...

    an electron has a magnetic field around it and so as a result as the current increases so does the magnetic field. This magnetic field is then concentrated within an iron core (the iron nail) to create the electromagnet and the electromagnet gets stronger with the increasing electrons.

  1. Physics Case Study - Do Sunbeds Cause Skin Cancer?

    o The lamps in sun-beds are becoming increasingly strong, putting out stronger and stronger rays, this is not monitored by any sort of safety agency, so overexposure is a likely danger. o There is no set age precautions made by the government, children as young as nine have been reported

  2. Refractrometry. Aim: Using a model Pulfrich refractometer determine the refractive index of a range ...

    You should remember to make a note on this piece of paper what concentration was used. 10. After thoroughly washing the block to remove any traces of the sugar solution, repeat using a clean sheet of white paper and a clean strip of black paper for the rest of the solutions including the unknown concentrations.

  1. Carry out an experiment to find a relationship between the incident angle and the ...

    I will insert the light slit into the light box and shine the beam of light at the Perspex block, from the selected angles. Marking crosses at the point at which the light exits the Perspex and where it continues to travel.

  2. Investigate how the speed of light differs in air and in Perspex.

    fig.1 I predict that the graph of sin I over sin r will be a straight line through the origin. As sin I over sin r is a constant. Diagram Methodology * Place Raybox on a sheet of plain white a3 paper and drawaround it.

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