Required Practical 1: Microscopes

• Optical microscope


  Used to look at cells on a prepared microscope slide
• Optical microscope


  • Has a stage to place the microscope slide
  • Has a light source (lamp or mirror) to illuminate the slide
  • Has objective lenses with different magnifications (4x, 10x, 40x)
  • Has an eyepiece lens with 10x magnification
  • Has coarse and fine focusing dials
• Using an optical microscope to view a prepared slide


  1. Place slide on stage and secure with clips

  2. Select lowest power (4x) objective lens

  3. Slowly turn coarse focus dial to lower lens until it almost touches slide

  4. Look through eyepiece and turn coarse focus dial to bring cells into focus

  5. Use fine focus dial to sharpen focus

  6. Calculate total magnification by multiplying eyepiece (10x) and objective (4x, 10x, 40x) lens magnifications
• What you might see under an optical microscope


  • Animal cells: nucleus, cytoplasm, cell membrane, possibly mitochondria
  • Plant cells: cell wall, cytoplasm, nucleus, possibly vacuole and chloroplasts
• An optical microscope can only show limited detail compared to other microscopes
• A drawing of the cells should include a magnification scale
• eye piece has a magnification of 10x and the low-power objective lens has a magnification of 4x. calculate the total magnification?


  4x * 10x = 40x