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

Does the focal length of a lens depend on the colour of light used?

Extracts from this document...

Introduction

Physics coursework PSA3 experiment

Does the focal length of a lens depend on the colour of light used?

Aim

The aim is to investigate the Focal lengths of light in the visible spectrum.

Introduction

I intend on using light with as much difference in wavelength as possible so that I can compare my results with more ease and so that errors in my experiment do not lead to overlapping results that have no distinct difference in them. However as I am restricted to a school laboratory I shall be using light on the part of the electromagnetic spectrum visible to the human eye.  This is because filters for red and blue light can be found and used easily and have a large enough wavelength difference (red light with a wavelength of around 700nm whilst blue light is nearly 400nm) as they are on opposite parts of the visible spectrum to each other. Before I started the experiment I was given the lens I was going to use in the experiment so that I could work out the rough focal length of the lens.  This meant that I

...read more.

Middle

25.0

78.5

81.5

80.5

88.8

79.2

88.9

82.9

28.5

62.0

64.0

60.0

63.0

61.3

63.5

62.3

33.3

48.1

49.5

46.0

48.3

47.0

48.3

47.9

40.0

39.5

40.0

38.7

39.4

38.6

40.0

39.4

50.0

33.0

33.4

32.7

33.0

32.9

33.3

33.1

66.7

28.5

29.0

28.6

28.9

28.6

28.9

28.8

100.0

25.1

25.2

25.1

25.0

25.1

25.1

25.1

blue filter

U (cm)

V (cm)

V (1st repeat) (cm)

V (2nd repeat) (cm)

average V (cm)

minimum

maximum

minimum

maximum

minimum

maximum

20.0

210.0

235.0

212.0

230.0

215.4

230.0

222.1

22.0

140.0

162.0

145.0

165.0

144.0

161.0

152.8

25.0

75.5

84.3

78.5

82.0

79.7

83.0

80.5

28.5

60.3

62.0

59.1

62.2

59.5

62.5

60.9

33.3

47.5

48.2

45.7

47.6

47.0

48.1

47.4

40.0

39.2

38.7

38.3

39.1

38.0

38.7

38.7

50.0

33.0

33.4

32.3

32.6

33.0

32.6

32.8

66.7

28.5

28.7

28.2

28.7

28.4

28.8

28.6

100.0

25.4

25.5

25.0

24.7

25.2

25.4

25.2

red light

 reciprocal

...read more.

Conclusion

My aim was achieved but the conclusion is not very reliable.

Modifications

To make my results more accurate I could use auto focus technology that can be found in some projectors and cameras rather than the human eye (which has questionable reliability) to determine the focal point.  This will ensure that I have the smallest possible error in the perception of the best (most in focus) image distance.  And in my experiment I found the percentage error in the determining of the focal point to be over 10%.  Without this error my conclusion would still have been the same.  I could also use a see through lens holder because it was hard to determine the object distance using the lens holder provided, and because I was using reciprocal values a small difference is magnified when dealing with small object distances. I would also measure more distances to increase the reliability.  I would also use different lenses so that I could compare that affect to gain a more reliable conclusion.  And I would also a transparent lens holder designed to slide over a meter rule to increase he accuracy of my results.

...read more.

This student written piece of work is one of many that can be found in our AS and A Level Microscopes & Lenses 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 AS and A Level Microscopes & Lenses essays

  1. Peer reviewed

    Physics coursework; Finding the focal length of a lens using a graphical method.

    4 star(s)

    the screen can all be positioned at 90 degrees to the ruler. This ensures the equipment is aligned at all times along the principle axis. ==> I will take the required measurements by setting the distance u (which will begin at 250 mm (because that is a higher measurement than the rough focal length I will have found earlier,)

  2. To investigate the relationship between the distance between a lens and an object, and ...

    The object must be kept constant, as varying this could have a serious effect on the experiment. Some objects may appear more focused than others, depending on their colour, texture and size and therefore the object must be the same throughout the experiment The eyesight of the person observing is

  1. In this experiment I will be investigating the efficiency of a motor. I hope ...

    Glass is harder than plastic therefore it does not scratch easily and it can then help produce a clear image. The material does not easily deform therefore the focal point can remain constant. Glass is good at transmitting light; it absorbs very little.

  2. To investigate the relationship between u and v for a convex lens.

    There are some problems with the experiment. The first being that even though the object was pushed up to the lamp some light was still escaping.

  1. Finding the Focal Length of a Lens.

    * The red and green light did not focus at the same points; therefore the focal length is dependant on the wavelength and/or frequency of the light. * When one of the coloured lights was focused, it wasn't focused at a single point, but over a range of distances (u and v).

  2. Relationship Between U and V For a Convex Lens

    field of the image, along with the relative sharpness of objects in the image. Secondly red was chosen over the other thin lens. This was because the other thin lens produced an image much further away, making it harder to take results of other distances of u below it.

  1. Lenses experiment

    So now I will do that. Here are some ray diagrams, the object in each is 2.0cm tall and the focal length of the lens in each diagram is 4.0cm. In the first ray diagram the object is between the focal point and the lens this giving a virtual image.

  2. How has the Invention of Contact Lenses affected people's Sight?

    So it is very common nowadays to see people wearing eye contacts even though they don't need them for their sight. However, a prescription is always needed because wearing contact lenses is still considered as a medical application. And the fact that they are more and more common in today's

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