Refraction by Spherical Surfaces: Practice Problem & Solution

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:

The powers of the lenses are $P_1 = \frac{100}{80} = 1.25 D$ and $P_2 = \frac{100}{-50} = -2.0 D$. The resulting power of the combination is $P = P_1 + P_2$. $P = 1.25 - 2.0 = -0.75 D$.