• 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...

Introduction

Christopher Yu

Investigating the Power of a Diverging Lens

Aim:

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

Outline:

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.

Variables:

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.

Method:

  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.

Middle

Analysis

        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.

image00.png

image01.png

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

image04.png

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,

TABLE 1

...read more.

Conclusion

± 0.001

0.350

2.230

2.270

2.250

-6.69

± 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,

TABLE 2

Absolute Minimum Length for Clarity (m)

Absolute Maximum Length for Clarity (m)

0.659

0.701

0.749

0.791

0.829

0.871

0.929

0.971

2.229

2.271

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

TABLE 3

Lower Boundary Power (D)

Upper Boundary Power (D)

Mean Power (D)

Error of Mean Power (D)

-6.670

-6.750

-6.710

±0.040

-6.670

-6.700

-6.685

±0.015

-6.570

-6.620

-6.595

±0.025

-6.420

-6.460

-6.440

±0.020

-6.690

-6.700

-6.695

±0.005

Average

-6.625

±0.021

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. Peer reviewed

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

    4 star(s)

    Similarly the angle of the screen may not have been at exactly a 90 degree angle to the ruler, (though I can be sure its base was.) These limitations may have the effect of making my conclusions inaccurate because they could have affected my measurements of u and v, from

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

    This meant I could not sketch the uncertainties, yet I could analyse the uncertainty between the two intercepts. Power Result: Y axis: At the intercept, 1/U=0 and so the 1/V reading will give us the estimated power (1/F). X axis: Referring to 1/V=1/U+1/F, looking at the X axis intercept I

  1. Lenses experiment

    1.15 10.0 20.0 Real same size & inverted 2.0 1.00 10.0 20.0 Real same size & inverted 2.0 1.00 10.0 20.0 Real same size & inverted 2.0 1.00 10.0 20.0 Real same size & inverted 2.0 1.00 10.0 22.0 Real diminished & inverted 1.5 0.75 10.0 22.0 Real diminished &

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

    For who (explanation of vision troubles) Contact lenses were designed for people who cannot see properly, and nowadays they are definitely developed enough to be able to correct almost all the vision troubles. The 5 main vision conditions are the following: * Astigmatism: this condition usually affects both nearsightedness and

  1. Finding the Focal Length of a Lens.

    The Method 1. Gather the required equipment: A lens, paper (to act as a screen), a stand to hold the screen, a double light source (plus power pack).

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

    The distance from the lens to the card, when the image is in focus gives the focal length. Ray diagrams are a simple way of demonstrating how light passes through a lens, and also why the effects happen. Ray diagrams: Convex Lens Concave Lens Considering the facts outlined above, I

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