Multiple choice

The magnifying power of a telescope can be increased

  1. by increasing focal length

  2. by fitting eye-piece of high power

  3. by decreasing focal length

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Telescope magnification is the ratio of objective focal length to eyepiece focal length. A high-power eyepiece has a shorter focal length, which increases this ratio and thus magnification. Simply "increasing focal length" is ambiguous without specifying which lens.

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