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:

Using Lens Maker's formula: $\frac{1}{f} = (\mu - 1)(\frac{1}{R_1} - \frac{1}{R_2})$. $\frac{1}{f} = (1.5 - 1)(\frac{1}{20} - \frac{1}{-20}) = 0.5 \times \frac{2}{20} = \frac{1}{20} cm^{-1}$. So focal length $f = 20 cm = 0.2 m$. Power $P = \frac{1}{f(m)} = \frac{1}{0.2} = +5D$.