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 and slowly lower it until it almost touches the slide

  3. Look through eyepiece and slowly turn coarse focus dial until cells come into focus

  4. Use fine focus dial to bring cells into clear focus

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

  • Animal cells: nucleus, cytoplasm, cell membrane, possible mitochondria
  • Plant cells: cell wall, cytoplasm, nucleus, possible vacuole and chloroplasts
• An optical microscope can only show limited detail, it cannot see organelles like ribosomes or Golgi apparatus
• A magnification scale should be included on drawings made from an optical microscope
• This is a required practical that could come up as a 6 mark essay question in the exam