microscopes

• What methods helped scientists discover internal cell structures?

  Microscopes and cell fractionation
• What are the three key types of microscopes mentioned?

  Optical, transmission, scanning electron
• What is the definition of magnification?

  How many times larger the image is
• What does resolution or resolving power refer to?

  Minimum distance to view objects separately
• What determines the resolution in optical microscopes?

  The wavelength of light
• What determines the resolution in electron microscopes?

  The wavelength of the beam of electrons
• What is the main advantage of optical microscopes?

  They can produce color images
• Why do electron microscopes have higher resolution?

  Electrons have shorter wavelengths than light
• What type of images do electron microscopes produce?

  Black and white images
• Why can't living samples be viewed in electron microscopes?

  Samples must be in a vacuum
• What is the function of a transmission electron microscope?

  To pass electrons through a specimen
• What type of image does a transmission electron microscope produce?

  2D black and white images
• What does a scanning electron microscope do?

  Scatters electrons off the specimen's surface
• What type of image does a scanning electron microscope produce?

  3D images
• What is the formula for magnification?

  Image size = actual size × magnification
• How do you convert millimeters to micrometers?

  Multiply by 1000
• How do you convert micrometers to millimeters?

  Divide by 1000
• What is the magnification if the image size is 20 mm and actual size is 50 µm?

  400 times magnification
• What is an eyepiece graticule?

  A glass disk with a scale etched on it
• Why must the eyepiece graticule be calibrated?

  To account for different magnifications
• What is a stage micrometer?

  A glass slide with a scale for calibration
• How do you calibrate the eyepiece graticule?

  Align it with the stage micrometer scale
• What is the relationship between eyepiece graticule divisions and stage micrometer divisions?

  They vary based on magnification
• If one division on the eyepiece graticule is worth 5 µm, how long is 13 divisions?

  65 µm
• What are the key differences between optical and electron microscopes?

  • Optical microscopes:
  • Lower resolution
  • Can view living samples
  • Produce color images
  • Electron microscopes:
  • Higher resolution and magnification
  • Cannot view living samples
  • Produce black and white images
• What are the steps to calibrate an eyepiece graticule?

  1. Place stage micrometer on the stage.
  2. Align eyepiece graticule with stage micrometer.
  3. Count divisions on eyepiece fitting into micrometer.
  4. Calculate the value of one eyepiece division.
• What are the key points to remember about microscopes?

  • Optical microscopes have lower resolution.
  • Electron microscopes have higher resolving power.
  • Magnification formula: image size = actual size × magnification.
  • Eyepiece graticule must be calibrated for accurate measurements.