Light Microscopy

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  • Created by: EvieWong
  • Created on: 16-04-18 21:10

Light Microscopes

  • Invented in the 1590s
  • Let us see things liike nuclei and chloroplasts
  • Can be used to look at living tissue
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Eyepiece Lens

  • At the top of the microscope
  • Looked through to see the image
  • Magnifies the image (usually by x10)
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Objective Lens

  • Magnify the image
  • Usually three objective lens which can be changed
  • Normally x4, x10, x40 (on top of the magnification from the eyepiece lens)
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Stage

  • Holds the slide
  • Supports the specimen/tissue
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Clip

  • Holds the specimen in place on the slide
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Lamp

  • Underneath the stage
  • Shines light through the slide
  • Allows the image to be seen more easily
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Focusing Knobs

  • Move the stage up and down
  • Bring the image into focus
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Slide

  • Rectangle of clear glass/ plastic
  • What the specimen is placed on
  • Held in place by the clips
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Cover Slip

  • Square of thin, transparent plastic or glass
  • Goes over the specimen on the slide
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Preparing Specimens

1. The specimen needs to let light through it, so thick specimens need to be sliced more thinly.

2. Use a pipette to put a drop of water or mountant (a clear gloopy liquid) on the slide to secure the specimen in place.

3. Place the specimen on the slide using tweezers.

4. Stain the specimen if required. Different stains colour different structures or tissues in the cell.

5. Carefully lower a cover slip over the specimen and press it down gently, so no air bubbles are trapped under it.

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Viewing Specimens

1. Clip the slide onto the stage.

2. Start with the lowest powered objective lens (usually x4).

3. Use the coarse adjustment knob to move the stage up to just below the objective lens.

4. Looking down the eyepiece, move the stage downwards usung the coarse adjustment knob, until the specimen is just about in focus.

5. Adjust the focus with the fine adjustment knob until there is a clear image of the specimen.

6. If needed, a greater magnification and higher powered objective can be used. Refocus the microscope with the fine adjusment knob.

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Total Magnification=Eyepiece Lens x Objective Lens

  • Equation relating total magnification, eyepiece lens magnification, and objective lens magnification

Total Magnification= Eyepiece Lens Magnification x Objective Lens Magnification

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Magnification= Image Size/ Real Size

  • Equation relating magnification, image size, and real size
  • The image size and real size should be in the same units for the equation

Magnification= Image Size/ Real Size

Image Size= Magnification x Real Size

Real Size= Image Size/ Magnification

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