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An astronomer wishes to improve the resolving power of an astronomical telescope to clearly distinguish two closely spaced binary stars. Which of the following modifications will successfully achieve this?

Options

  1. AIncrease the wavelength of the incident light
  2. BIncrease the focal length of the objective lens
  3. CIncrease the diameter of the objective lens
  4. DDecrease the diameter of the objective lens

Correct answer

C. Increase the diameter of the objective lens

Step-by-step solution

The resolving power of an astronomical telescope is given by the relation: Resolving Power = D 1.22 where D is the diameter (aperture) of the objective lens and is the wavelength of the incident light. From this expression, the resolving power is directly proportional to the diameter of the objective lens and inversely proportional to the wavelength of light. Therefore, to increase the resolving power, one must increase the diameter of the objective lens. Changing the focal length affects magnifying power, not reso

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