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Year 9 iGSCE - Biology Microscope

You will mostly be using a compound microscopes through out your education.



In most cases the eye piece magnifies the image by 10.

The weakest object is 4 magnification, then 10 magnification and a max of 40 magnification. Some compound microscopes can have objects of 100 magnification.

This means the image is magnified to:

4 x 10 = 40 times the original image


10 x 10 = 100 times the original image


40 x 10 = 400 times the original image


We can calculate the length of a magnified object by using the magnification of the lens.

Length of object = length of magnified object / magnification

For example, if a specimen looked 10mm in length under a microscope at a magnification of 1,000 times, the calculation of the actual length would be:

Length of object = 10 ÷ 1000 = 0.01 mm

How to

1. Set the microscope on the lowest magnification

2. Place the microscope slide on the stage and fasten it with the stage clips.

3. Turn the focus knob so the stage moves upward. Move it up as far as it will go without letting the objective touch the cover slip.

4. Look through the eyepiece and move the focus knob until the image comes into focus.

5. Adjust the light intensity for the greatest amount of light.

6. Move the microscope slide around until the sample is in the centre of the field of view

7. Use the focus knob and the fine focus knob to place the sample into focus and readjust the light intensity for the clearest image.

8. When you have a clear image of your sample with the lowest power objective, you can change to the next objective lenses.

9. You might need to readjust the sample into focus and/or readjust the condenser and light intensity.

10. When finished, lower the stage, click the low power lens into position and remove the slide

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