2.1.2 Microscopes

• What does magnification refer to in microscopy?

  How many times larger the image is
• What is resolution in microscopy?

  The minimum distance between two objects
• What type of microscope uses the wavelength of light?

  Optical microscope
• What type of microscope uses the wavelength of a beam of electrons?

  Electron microscope
• How does an optical microscope create an image?

  A beam of light is condensed
• Why does an optical microscope have poor resolution?

  Because light has a longer wavelength
• What are the characteristics of images seen with an optical microscope?

  Lower magnification, color images
• What are the advantages and disadvantages of optical microscopes?

  Advantages:

  • Living samples can be examined
  • Produces color images

  
  

  Disadvantages:

  • Poor resolution
  • Small organelles are not visible
• How does a transmission electron microscope work?

  Thin specimens are stained and placed in a vacuum
• What happens to electrons in a transmission electron microscope?

  Some parts absorb electrons and appear dark
• What type of image does a transmission electron microscope produce?

  2D image
• How does a scanning electron microscope work?

  Electrons are beamed onto the surface
• What type of image does a scanning electron microscope produce?

  3D image
• How is image size calculated in microscopy?

  Image size = Actual size x Magnification
• What are the units of measurement in microscopy?

  • m (meters)
  • mm (millimeters)
  • µm (micrometers)
  • nm (nanometers)
• What is the purpose of an eyepiece graticule?

  To measure the size of objects
• What is a stage micrometre used for?

  To calibrate the eyepiece graticule
• What is the size of one dimension on the micrometer?

  10 µm