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Minor Versionm

by Procheta Mallik


Make your own microscope using a 2.5 mm dia Glass Bead. Prepare the slide of a thin layer of onion peel, garlic peel, cheek cells, etc by placing it on the given slide, staining it with safranin and placing the cover-slip over it. Observe the cells and draw the structure as you see.

The first simple microscopes began to appear in the 13th century, but the optical properties of water and glass have been used to magnify things for centuries.

    • Exercise caution when using paper cutter/scissor

  1. Take an ice cream stick and mark two points 4 cm from each end.
    • Take an ice cream stick and mark two points 4 cm from each end.

    • At the marking measure the width of the ice cream stick and mark the midpoint on both sides .

    • At the midpoint markings make two holes using the tip of a scissor blade.

    • Rotate the blade gently to make a neat circular hole, one for each bead

    • Be gentle with the ice cream stick as it may split/break/divide while making the holes

    • Make sure that each hole is just smaller than the size of the respective bead.

    • Hole for 2.5 mm bead.

    • Hole for 5 mm bead.

    • Take a cutter and clear the wood grains formed during piercing holes on the ice cream sticks.

    • Place the beads carefully in their respective holes on the ice cream stick

    • Insert the beads gently by pressing down to ensure they sit tight and snug in their respective holes

    • Make sure that your hands are clean and that you don't scratch or stain the glass beads while handling them.

    • Fixing 2.5 mm bead.

    • Take a small piece of insulation tape and make a diamond cut on the tape.

    • Take the insulation tape with diamond cut and fix the 2.5mm bead using it.

    • Place the 5 mm bead on the bigger hole.

    • Make a small hole at the centre of the foam piece; the size of the hole should be slightly less than the diameter of the 5mm bead such that no stray light interferes with your final microscopic image.

    • Make a hole on the insulation tape as in Step 4. Make sure that the hole is not more than the size of hole on the foam.

    • Now stick the cut tape on the foam and place the foam on the ice cream stick such that half of the bead comes out of the hole present in the foam.

    • Finished 5 mm bead microscope.

    • Finished 2.5 mm bead microscope.

    • Fill the observation table

    • A scratched bead may produce an unclear image

    • If the holes on the tape pieces or foam piece are too large, stray light and the natural spherical aberration of the bead could adversely affect the quality of your image

    • If you don't see sharp and clear image it implies that the distance between the bead and object has to be changed. Push the bead to the maximum distance you can. Then move the ice cream stick up a little to achieve focus.

    • Cut about an eighth of an onion. Take out one slice from the cut part to get the appropriate size of an onion peel

    • Bend the onion slice towards the concave side to make a small tear.

    • Carefully detach one side of the onion slice and pull out the transparent peel.

    • Cut the onion peel to a size smaller than that of the cover slips.

    • Wet the glass slide first with water and place the onion peel on it carefully.

    • Try to make the space between the onion peel and the slide free of air bubbles as much as possible; that is the reason we wet the slide.

    • Add a few drops of stainer (safranin) to the peel and keep it open for 30 seconds.

    • Now gently place a glass cover slip over the peel. To avoid entrapment of air bubbles, make sure to keep the cover slip at an angle initially while placing it on the slide.

    • See the onion cells through the 2.5mm bead on the microscope.

    • Make sure that the slide is very close to the bead and that your eyes are also extremely close to the bead on the other side. Adjust these distances infinitesimally to reveal a focused image!

    • Point the slide towards a source of light while viewing; do not point directly at the Sun.

    • A photograph of the peel under the microscope

    • Glass slide and cover slip not clean due to which image is not clear.

    • Didn't wet the slide initially, which causes air bubbles to get trapped beneath the onion peel.

    • Cover slip moving while hovering the microscope over it. Make sure excess safranin has been blotted out.

    • Fill the observation table

    • Try the same procedure with garlic.

    • Try with different stainer (Iodine)

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