Utiliser un microscope

METHOD DOCUMENT: Using a light microscope

PROCEDURE :

 Place the slide on the microscope stage, fix it with the stage clips and move it until the specimen directly is over the centre of the glass circle on the stage.

 Turn on the light with the dimmer on the lowest position.

 Put the lower power objective on, then focus using first the coarse knob, then the fine focus knob.

 Adjust the Diaphragm and the light dimmer as you look

through the Eyepiece, and you will see that more detail is visible when you allow in less light! Too much light will give the specimen a washed-out appearance.

 Move the specimen slowly until you centre it.

Once you have found the specimen on low power (100x), unless specifically asked to draw it on low power, centre the specimen in your field of view, then, without changing the focus knobs, switch it to High Power. If you don’t centre the specimen you will lose it when you switch to high power.

Once you have it on High Power remember that you only use the fine focus knob!

- The High Power Objective is very close to the slide. Use of the coarse focus knob will scratch the lens, and crack the slide. More expensive sounds . . .

OBSERVATION DRAWING (see method document)

To calculate the total magnification you have to multiply the eye piece lens magnification by the objective lens magnification

AFTER USE

Put the lower objective back in place, lower the stage, turn the light off and put the dimmer in the lowest position.

Clean the table, tidy instruments you used, place the slides in the bucket on teacher desk (small plastic container).

EVALUATION:

○ Quality of the settings (light dimmer, diaphragm).

● The right use of the objectives and knobs.

○ The choice of the best objective.

● The focus and the centre of the specimen to observe.

○ The cleaning, tidying and storage of lab equipment.

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