Question

Solve these numericals

c. If the sum of focal length and radius of curvature is $30cm$, what is the focal length of that spherical mirror?

Answer 1

Step 1 - Given data and formula.

The sum of the focal length $\left(f\right)$ and the radius of curvature $\left(R\right)$ of the spherical mirror is $30cm$.

That is $R+f=30cm$
The formula for the radius of curvature is $R=2f$

Step 2 - Finding the focal length

Substitute the value of $R$ into the equation to find the focal length.
$$\begin{gathered} 2f+f=30cm \\ 3f=30 \\ f=\frac{30}{3} \\ f=10cm \end{gathered}$$

Final answer - Hence, the focal length of a spherical mirror is $10cm$.