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

Find the refractive index of a plastic block.

Extracts from this document...

Introduction

Name        Jonathan Tam                Class: 13A

Yew Chung International School                Physics

Aim:        Find the refractive index of a plastic block

Method:

I will use two methods to find the refractive index of plastic. The first one is to use the critical angle, and the other one is to use Snell’s Law.

Critical Angle method:

image00.png

  1. Set up the apparatus as shown. Put a piece of white paper under the apparatus. Turn off lights from the surroundings.
  2. Put a black slid into the light box so that only a thin ray will be shone.
  3. Turn on the light box. Adjust the angle of incidence so that there are no refracted rays.
...read more.

Middle

image10.png to get refractive index of plastic.Repeat step 3 to 6 at least 7 times to get sufficient readings. Use a different angle of incidence each time.Compare the values obtained using the two methods.

Data Collection:

Critical angle method:

Critical Angle (± 0.5°)

47

48

47

Snell’s Law method:

Angle of Incidence (± 0.5°)

Angle of Refraction (± 0.5°)

32

24

15

11

45

32

70

42

53

36

85

48

28

21

...read more.

Conclusion

image03.png is 1.

image04.png

image05.png

0.530

0.407

0.259

0.191

0.707

0.530

0.940

0.669

0.799

0.588

0.996

0.743

0.469

0.358

The refractive index of plastic using Snell’s Law is: 1.344 ± 0.06

Conclusion and Evaluation:

From the two experiments, the refractive index of plastic is coherent to be between 1.344 to 1.36.

There are many systematic errors in these experiments, which came from the apparatus itself. These include:

  • protractor
  • light box

The protractor has a very high uncertainty of ± 0.5°. This has generated a high percentage error in our results (from 0.6% up to 3.3%). When we take sin for both angles and add the two percentage errors (or uncertainties) together, it has generated a whole range of refractive indexes.

However these results are acceptable because they both fall within the range of uncertainties (i.e. no contradictions). Therefore these experiments, although carries a high percentage error, can still be considered as valid.

...read more.

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

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

    4 star(s)

    (Snell's law). The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant for two given media. This constant is the refractive index (n). When referring to light, this is also known as the optical density and, as with

  2. Marked by a teacher

    Investigation:To find the refractive index of cooking oil.

    4 star(s)

    I therefore predict that the refractive index of cooking oil will be approximately 1.40. DEPENDENT VARIABLE (things to be kept the same) In order to make this investigation a fair test, several pointers must be followed throughout the experiment. These are: * The plastic tray, which is being used to

  1. Deviation of Light by a Prism.

    box can handle, and even at this temperature the ray box can get very hot. Care with he sighting pins also has to be taken into account even though they are really a minor issue, they are still sharp so common sense should prevail when using them.

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

    Cut a strip of black paper exactly the half the length of the block and the same thickness of the block. 4. Soak the piece of black paper in a sugar solution and place on the side of block as shown in the diagram (this forms a very thin layer of solution between the block and the paper).

  1. Light is so common that we often take it for granted.

    Each type of atom can produce only certain colours. Scientists can learn what kinds of atoms make up a light source by observing what colours are present in the light. They direct the light through an instrument called a spectrometer to separate the colours. The spectrometer may be a simple prism or it may be a more complicated device.

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

    From the scatter graphs I can see little difference when only looking at it so I can only say that they both have a positive direction but I wouldn't comment on how steep the line is because the two values of the variables within the two graphs are not in

  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. Investigating the factors which affect the sideways displacement of a light ray through a ...

    Then I will extend the incident ray so that it continues through and out of the glass block. This is called the original ray. To find the sideways displacement I must measure using a mm ruler the length between the emerging ray and the original ray.

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