NEETPhysicsGeometrical OpticsMCQ+4 / −1
A small telescope has an objective of focal length and an eye piece of focal length . The magnifying power of telescope for viewing a distant object is:
- A34
- B28
- C17
- D32
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Correct answer: B
The magnifying power of a telescope when viewing distant objects can be calculated using the formula:
$$ \text{Magnifying Power} (M) = \frac{\text{Focal Length of Objective Lens} (f_o)}{\text{Focal Length of Eyepiece Lens} (f_e)} $$
Given in the problem:
- Focal Length of Objective Lens, $f_o = 140 \mathrm{~cm}$
- Focal Length of Eyepiece Lens, $f_e = 5.0 \mathrm{~cm}$
Substituting these values into the formula gives:
$$ M = \frac{140 \mathrm{~cm}}{5.0 \mathrm{~cm}} = 28 $$
Thus, the magnifying power of the telescope is 28. The correct answer is Option B.
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