Rankers Physics

Refraction by Spherical Surfaces: Practice Problem & Solution

Two thin lenses of focal lengths $f_1$ and $f_2$ are in contact and coaxial. The power of the combinations is: (2008)
$\frac{f_1 + f_2}{f_1 f_2}$
$\sqrt{\frac{f_1}{f_2}}$
$\sqrt{\frac{f_2}{f_1}}$
$\frac{f_1 + f_2}{2}$

Solution Explained:

To solve this problem, we apply the core principles of Refraction by Spherical Surfaces. Understanding the underlying formula is key to arriving at the correct answer below:

Power of the combination is the sum of individual powers. $P = P_1 + P_2 = \frac{1}{f_1} + \frac{1}{f_2} = \frac{f_1 + f_2}{f_1 f_2}$.

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