The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

Explanation

To find the focal length of a spherical mirror given its radius of curvature, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Given Information:**
- The radius of curvature (R) of the spherical mirror is given as 20 cm.

2. **Recall the Relationship Between Focal Length and Radius of Curvature:**
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