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T. Trimpe 2005 http://sciencespot.net/ Why do we use a microscope? • Many things are smaller than we can see with the naked eye. To accurately study Biology we need a tool to help us see these tiny things. History • Antony van Leeuwenhoek is credited with developing the first microscope in about 1665. Although the compound microscope was already in use, what made Antony’s invention special was that he was able to magnify his ‘wee beasties’ by up to 270X. • Antony was the first to see bacteria, red blood cells, yeast and so much more! Body Tube Ocular lens (Eyepiece) Nosepiece Objectives Arm Stage Stage Clips Coarse Adjustment Diaphragm Light Fine Adjustment Base Always carry a microscope with one hand holding the arm and one hand under the base. What’s my power? To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective. What are the powers of magnification for each of the objectives we have on our microscopes? Fill in the table on your worksheet. Comparing Powers of Magnification We can see better details with higher the powers of magnification, but we cannot see as much of the image. Which of these images would be viewed at a higher power of magnification? The proper way to carry your microscope. • Always carry the microscope with two hands, holding it close to your body. Improper carrying. • Carrying the microscope like this could result in your ruining a very expensive piece of equipment. • The microscope should always be stored with the 4X (red) lens in place and the stage in its lowest position. • Always store your microscope in its numbered position, with the dust cover in place. How to focus your image • Place the slide on the stage, held in place by the stage clip. • ALWAYS start with the 4X lens. Focus your image. • Move to the 10X lens, focus. • NEVER use the coarse focus higher than 4X. • Repeat at the 40X lens, focus using the fine focus. Distance between lens and slide • Use only the fine focus knob with the 40X and 100X lens. Cleaning • Please use only lens paper to clean the lenses, never paper towels or Kimwipes. • Never use dry lens paper to clean eyepieces. Use the cleaning solution provided or breathe on the surface to be cleaned, then wipe. Let’s give it a try ... 1 – Turn on the microscope and then rotate the nosepiece to click the red-banded objective into place. 2 – Place a slide on the stage and secure it using the stage clips. Use the coarse adjustment knob (large knob) to get it the image into view and then use the fine adjustment knob (small knob) to make it clearer. 3 – Once you have the image in view, rotate the nosepiece to view it under different powers. Draw what you see on your worksheet! Be careful with the largest objective! Sometimes there is not enough room and you will not be able to use it! 4 – When you are done, turn off the microscope and put up the slides you used. How to make a wet-mount slide … 1 – Get a clean slide and coverslip from your teacher. 2 – Place ONE drop of water in the middle of the slide. Don’t use too much or the water will run off the edge and make a mess! 3 – Place the edge of the cover slip on one side of the water drop. 4 - Slowly lower the cover slip on top of the drop. Cover Slip Lower slowly 5 – Place the slide on the stage and view it first with the red-banded objective. Once you see the image, you can rotate the nosepiece to view the slide with the different objectives. You do not need to use the stage clips when viewing wet-mount slides! Weevil, 75X Mosquito head, 200X