Microscope Overview Natural Science

Microscopes Cost is between $600-$800 so be careful with them! Proper behavior will be used at all times Failure to do so will result in a loss of lab privilege, points, and an alternate assignment.

General Procedures Make sure all backpacks and books are out of the aisles before you get a microscope ALWAYS carry the microscopes with two hands – One hand on the arm and one hand on the base – Do not run or walk fast with a microscope

Parts of the microscope Eyepiece – The lens one looks through on a microscope. Usually 10x. Objective lenses – The lenses closes to the object one is viewing. – Held in a revolving nosepiece. – 4x (scanning) 10x (low power), 40-43x (high power), 100x (oil immersion) Stage – The platform on which the slide is placed. Often fitted with a mechanical stage to hold the slide and move the slide using stage controls. (Alternatively, slide clips are used to hold the slide.) Arm – Supports the lens systems. Iris diaphragm – Controls the amount of light passing through the object. Condenser lens – Focuses light under the object. Focusing knobs – Coarse focus—used for focusing under scanning and low powers only – Fine focus—used for focusing under high and oil powers primarily

Magnification Eyepiece – 10X Objective Lens – – Red 4 – Yellow 10 – Blue 40 Total magnification Calculations – Ex: low power, medium power, high power

Remember these things when using a microscope! Any excess cord of the microscope must be placed on the table Always start and end with LOW power

Always adjust the coarse focus knob first and then use the fine adjustment knob If you see only your eyelashes, move closer to the eyepiece If you wear glasses, take them off.

Use of Microscope Place slide on the microscope stage with the specimen directly over the center of the glass circle on the stage (directly over the light) – This will give you a 90% chance of finding the specimen as soon as you look through the eyepiece If you see a dark line that goes part way across the field of view, try turning the eyepiece. This line is a pointer that is very beneficial to point out different structures.

If and ONLY if you are on low power, lower the objective lens to the lowest point, then focus the course knob. (Then the fine focus knob) Adjust the diaphragm as you look through the eyepiece, and you will see that more detail is visible when you allow less light through. – Too much light will give the specimen a “washed- out” appearance

Once you have found the specimen on low power, (unless asked to draw the specimen on low power), center the specimen in your field of view Without changing the focus knobs, switch it to high power. – If you do not center the specimen before you switch objectives, you will lose the specimen

Use of Microscope Cont. Once you have the microscope on high power, remember to use only the FINE focus knob. Using the coarse focus knob will scratch the lens and crack the slide.

Microscope Specimen Drawings Use ONLY pencil – Drawings in pen are unacceptable Drawings must include clear and proper labels! All microscope drawings should be drawn inside the “field of view” circle include the specimen name. include the magnification (ex: 100x or 400x)

Specimen Drawings All structure or specimen labels should be on the outside of the circle All arrows should end with the point touching the object to be labeled Animal cells should always include the following five labels: cell membrane, nuclear membrane, nucleus, cytoplasm

Cont. Specimen Drawings Plant cells should always include the following seven labels: cell membrane, cell wall, nuclear membrane, nucleus, central vacuole, cytoplasm, chloroplast (not all plant cells have these) In your drawings you will be applying your knowledge of cells. All field of view drawing MUST be labeled to receive the points for the activity.

REMEMBER!!! Be careful with the lab equipment, and be sure to leave the lab in the same condition it was when you arrived. Enjoy looking at specimen under the microscope!