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The focal length of the objective lens of a telescope is 50 cm. If the magnification of the telescope is 25, then the focal length of the eyepiece is
  • a)
    12.5 cm
  • b)
    5 cm
  • c)
    2 cm
  • d)
    10 cm
Correct answer is option 'C'. Can you explain this answer?
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Focal Length of Objective Lens:
The focal length of the objective lens of a telescope is given as 50 cm. The objective lens is responsible for collecting light and forming an image of the distant object.

Magnification of the Telescope:
The magnification of the telescope is given as 25. Magnification is the ratio of the apparent size of an object as seen through the telescope to its actual size.

Finding the Focal Length of the Eyepiece:
To find the focal length of the eyepiece, we can use the formula for the overall magnification of a telescope:

Magnification = -focal length of objective lens / focal length of eyepiece

Rearranging the formula, we can solve for the focal length of the eyepiece:

focal length of eyepiece = -focal length of objective lens / magnification

Substituting the given values, we have:

focal length of eyepiece = -50 cm / 25
focal length of eyepiece = -2 cm

Since focal lengths cannot be negative, we take the absolute value of the result to obtain the positive value:

focal length of eyepiece = 2 cm

Therefore, the correct answer is option C) 2 cm.
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The focal length of the objective lens of a telescope is 50 cm. If the magnification of the telescope is 25, then the focal length of the eyepiece isa)12.5 cmb)5 cmc)2 cmd)10 cmCorrect answer is option 'C'. Can you explain this answer?
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