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

Focal length of Concave and Convex lens

Extracts from this document...


          Focal length of Concave and Convex lens


In this experiment, we are going to use three different methods and one method to find the focal length of an unknown-focal length of convex lens and concave lens.


2 meter rules, a light box, a white-coloured screen, a D.C. power supply, 2 lens holders, a plane mirror, a transparent object F, two-unknown focal length of convex and concave lens.


Since the convex and concave lenses are made of glasses, the focal lengths are actually the convergent point of all refracted light sources. So, the main theory that we are applying is the refraction theory and also the Lensmaker's equation.

is an equation which shows the relationship between the focal length with the object and image distances. With mathematical simplification, the Lensmaker's equation can be applied as follow image00.png.


Type A is a convex lens with shorter diameter

...read more.


First, put a light source with a transparent object F in front of a convex lens.

Then adjust the distance between the lens and the light source and mark down the distance as D when you can form a sharp image on the screen allocated right beside the light source. The length D is the focal length

METHOD IIIimage04.png


By putting the light source in front of the lens and then adjust the distance between the lens and light source and the lens and the screen. Obtain a sharp image and mark down the distance of U and V.

Then plot a graph with U and V to find out the focal length of the lens by applying the equationimage00.png.

Concave lensimage06.png


Place the light source in front of the convex lens which is placed between the concave lens and the light source.

...read more.


Actually, whenever we test the focal length of the lenses we need to consider the degree of the curve of the lens. Since some light rays may refracted near the edge of the lenses and the refracted ray may thus get another focal length and thus resulting a unclear image.

On the other hand the nodal inside the lenses is another interesting topic that students should know. Although we cannot apply the knowledge of it in this experiment, I think most of us should know more about it. It is because this is another factor that affecting the degree of refraction of light rays in lenses.

Lastly, since light ray consist of 7different colours,and what we need to know that the distortion of the rays may happen. So we need to make the total distance of the experiment much smaller.

...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

    Investigation:To find the refractive index of cooking oil.

    4 star(s)

    If light does not travel through a material then the atom is not re-emitting the electron. Before I completed this investigation I predicted that the refractive index of cooking oil would be between the refractive index of water and glass.

  2. Deviation of Light by a Prism.

    ray above 90° would have to come from inside the prism itself. I have therefore chosen to take readings in the range of 30° - 85°. I will take one reading below 30° but this will only be taken to prove right my initial theory work and will not be taken into consideration in any conclusions that I draw.

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

    Experiment where the number of coil wraps is the variable- In this graph is a complication because the line of best fit doesn't start from 0 on the number of coils axis. So where the line of best fit touches this axis I will have to minus this value from the number of coils value in each formula.


    State any precautions, which may be necessary when connecting the two stages together. Document all results and explain all the terms commonly used in connection with filters e.g. dB points, roll off rate expressed in dBs, Corner/cut off frequency, time constant etc... Provide suitable comments where necessary. Part 2: 1.

  1. Formulation Of A Theory.

    Another reason is that it is an ordinary question used in most surveys and questionnaires in similar subjects. The steps that will be taken to avoid bias are to note down the people's estimations straight away with the truth being considered in order to avoid changing answers so that the hypothesis is right from the start.

  2. Sideways Displacement of a Light Ray

    * I will be careful in moving the equipment, so that everything will be safe * if something goes wrong - ask the teacher To make a fair test, I will pay attention to the next things: * use the same equipment (see above)

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