Shortcut Methods

Microscopes

1. Magnifying Power

  • Shortcut: Multiply the magnifying power of the eyepiece lens by the magnifying power of the objective lens.
  • Formula: M=me×mo

2. Resolving Power

  • Shortcut: Divide 1.22 by the numerical aperture of the objective lens, then multiply the result by the wavelength of light used.
  • Formula: R=1.22λNA

Telescopes

1. Magnifying Power

  • Shortcut: Divide the focal length of the objective lens by the focal length of the eyepiece lens.
  • Formula: M=fofe

2. Light-Gathering Power

  • Shortcut: Square the diameter of the objective lens, then multiply the result by pi and divide by 4.
  • Formula: G=πd24

Additional Numericals

Microscopes

  • Objective lens diameter: 4-10 mm
  • Eyepiece lens focal length: 10-25 mm
  • Eyepiece lens magnifying power: 5x-10x
  • Objective lens magnifying power: 4x-100x
  • Resolving power: 0.2-2.0 µm

Telescopes

  • Objective lens diameter: 50-200 mm
  • Eyepiece lens focal length: 20-50 mm
  • Magnifying power: 10x-1000x
  • Light-gathering power: 100x-100000x