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

Investigating the Power of a Diverging Lens

Extracts from this document...


Christopher Yu

Investigating the Power of a Diverging Lens


To find the power of a given diverging lens by using a pre-selected converging lens.


The power of two lenses placed together in line to an object will allow both of their powers to add together.

P1 + P2 = Ptotal

Therefore, by using a combination of 2 lenses, one of which the power is known, I can find the focal length of the combination of lenses and then calculate the total power. The power of the converging lens can be subtracted from the total power to find the power of the diverging lens.


Independent: Object distance

Dependent: Image distance

Control: Object size and shape, power of both lenses, material of both lenses

In my pre-tests, I have found that I obtain a reasonable range of results using a converging lens of 10 Dioptres that is larger than the power of the diverging lens therefore giving reasonable results.


  1. Set up apparatus as shown in diagram.
  2. Adhere the unknown diverging lens to the known, pre-selected converging lens with plasticine ensuring that the plasticine does not interfere with the light i.e. the plasticine does not cover the main central portion of the lenses.
...read more.



        After collecting all the results, I can plot the range of values of each different object distance with their corresponding image distance. To draw this graph and obtain a linear relationship, I can rearrange the thin lens formula to the linear graph form y = mx + c where y and x are variables, m is the gradient of the line and c is the y-intercept.



Where image02.pngandimage03.png but, because the formula can also be arranged thus,


That means that image05.pngwill be both the y-intercept andthe x-intercept, therefore giving a graph like this, where both intercepts are equal to the power (Power = reciprocal of focal length, P = f-1)

I will also include error analysis, which is shown here with a set of pre-test data using a converging lens of 10 dioptres,


...read more.


± 0.001






± 0.001

 Then the error in the object, image minimum, image maximum and image mean length will be ±0.001 but because the lengths are made into reciprocals, their errors become neither absolute nor percentage, therefore to calculate it, the maximum and minimum values must be used, so there will be 2 more columns where the error is added to the values,


Absolute Minimum Length for Clarity (m)

Absolute Maximum Length for Clarity (m)











If the values themselves are used to calculate the power of the diverging lens mathematically, it would be as such, including Table 1


Lower Boundary Power (D)

Upper Boundary Power (D)

Mean Power (D)

Error of Mean Power (D)
























Therefore the power of the diverging lens is –6.625 dioptres with an error of ± 0.021.

The graph can be drawn including these errors, and it makes it possible to draw a graph with a linear relationship where the x and y intercepts are equal – within the range of the error of the results – to find the correct power of the diverging lens.

See graph of pre-test results.

From the graph, the intercepts are at 3.3 D, therefore the resultant power of the combined lenses is 3.3 D. The pre-selected lens is 10 D, therefore,

10 + d = 3.3

d = 3.3 – 10

d = -6.7 D

So, the power of the diverging lens is –6.7 dioptres.

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

    This supports my hypothesis. I will now conduct an experiment to investigate my theory further. Apparatus: * Ruler * Screen of thick white paper * Photographic slide (as object) * Lens (focal length of 10cm) * Lens stand * Clamp stand * Power pack * Ray box Set-up diagram: Method:

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

    for U 0.5 200 0.25 tape measure (mm) (for V) 0.5 2360 0.02 focal range (mm) 263 236.0 11.14 Blue filter for U 20cm Apparatus name error in apparatus largest reading (cm) largest percentage error (%) meter rule (mm) for U 0.5 200 0.25 tape measure (mm) (for V)

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

    x 0.68 = 4.000032 = 4.00 0.4 x 0.9 = 0.36 0.36 / 4.00 = 0.08999928 x 100 = 9.00 0.5 1.29 4.56 1.0.72 2.0.77 3.0.75 Average: 0.75 1.29 x 4.56 x 0.75 = 4.4118 = 4.41 0.5 x 0.9 = 0.45 0.45 / 4.41 = 0.101999184 x 100 =10.20

  2. Lenses experiment

    magnified & inverted 8.9 4.45 10.0 14.0 Real magnified & inverted 4.4 2.20 10.0 14.0 Real magnified & inverted 4.6 2.30 10.0 14.0 Real magnified & inverted 4.3 2.15 10.0 14.0 Real magnified & inverted 4.5 2.25 10.0 16.0 Real magnified & inverted 2.9 1.45 10.0 16.0 Real magnified &

  1. Relationship Between U and V For a Convex Lens

    When the object is placed before the focal point, it means that the image becomes on the side of the lens, upright, magnified and virtual. This is because the middle rays passing through the centre of the convex lens, becomes so steep.

  2. My experiments focus is to obtain an accurate measurement for a specific lenss power.

    +/- 1 1/U (Dioptres) V Minimum (x10-3 M) V Maximum (x10-3 M) V Mean (x10-3 M) V +/- (x10-3 M) %V +/- 1/V Min. (D) 1/V Max. (D) 1/V Mean (D) 1/V +/- (D) 700 -1.43 196 200 198 2 1.01 5.10 5.00 5.05 0.0510 650 -1.54 198 204 201

  1. Use of the material Zerodur in the KECK observatory telescope. The very low CTE ...

    The CTE is determined by the percentage of the material that is crystalline and the percentage that is amorphous. In order to achieve the 0 expansion coefficient that is required for the usage in the KECK observatories, it is necessary to balance the mix of elements, cooling rate and amount

  2. An investigation into the workings of the opticians

    The eye may resemble a rugby ball rather than a sphere. This can cause different powers along different axis of the eye Acknowledgement of image: www.drsheingorn.com Myopia Also known as 'near' or 'short' sightedness this occurs when light is focused by the eye to a point in the vitreous fluid

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