Optical Instruments: Practice Problem & Solution
Four lenses of focal length $\pm 15 cm$ and $\pm 150 cm$ are available for making a telescope. To produce the largest magnification, the focal length of the eyepiece should be (1994)
Solution Explained:
To solve this problem, we apply the core principles of Optical Instruments. Understanding the underlying formula is key to arriving at the correct answer below:
Magnification of a telescope is given by $M = \frac{f_o}{f_e}$. For the largest magnification, the objective should have the maximum focal length and the eyepiece should have the minimum focal length magnitude. For an astronomical telescope, both lenses are convex, so the eyepiece should be $+15 cm$.
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