• 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. 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.

  1. Relationship Between U and V For a Convex Lens

    The virtual image has a negative distance from the lens, which means the image it is virtual. However at 14.9cm the largest distance of v is produced, after which the distance of v decreases. Variables * Independent variable My independent variable is u (object distance).

  2. The focal length of a convex lens.

    The image occurs behind you, (c) The pin is not along the principal axis of the lens, (d) The lens and the mirror are not parallel. In experiment 3, the lens must be placed vertically. In using the no-parallax method, you shouldn't only move your eyes, but also your head.

  1. Measuring the focal length of a lens for red and green light- Case Study

    Source: http://hcd2.bupa.co.uk/fact_sheets/html/myopia.html The second defect is known as hypermetropia (more commonly known as being long sighted) if a human suffers from hypermetropia a person cannot see objects that are closer to them as well as they can see objects that are a lot further away.

  2. Lenses experiment

    This should now indicate that as the object has been moved further away from the focal point the size of the images have decreased and when the magnification is worked out the magnifications should also decrease. This should now mean the any images after this should not be magnified or the same size but diminished.

  1. I intend to show how the position and nature of the image can be ...

    With object two the rays would have had less time to spread out and would therefore converge at an earlier point. Objects four and five will not appear on the far side of the lens as they will be going towards the lens at such at angle that they will

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

    * Focal point of lens used. * Light levels. * Size, shape and possibly colour of object used. * Eyesight of observer. * Angle of lens in relation to screen and object. * Colour and surface of screen. As I will only be investigating the effect of altering the distances

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