Question

Calculate the focal length of the concave mirror if it's radius of curvature is 45cm

Answer 1

Answer:

since f = R/2

so,

focal length = radius of curvature/2

= 45/2 = 22.5 cm

Answer 2

Answer:

-22.5cm is the required focal length of the concave mirror.

Step-by-step explanation:

Explanation:

Given, radius of curvature = 45cm.

• The focal length of a concave mirror is negative in the cartesian system.

• The focal length of a concave mirror is defined as the distance between its pole and its focus. Getting a true image of the far object allows one to measure the focal length of a concave mirror.

• A system with a positive focal length is said to converge light, and one with a negative focal length is said to diverge light.

And the relation between focal length and radius of curvature,

Focal length (f) = $\frac{Radius \ of \ curvature}{2}$ = $\frac{-R}{2}$

⇒f = $\frac{-45}{2}$ = -22.5cm.

Final answer:

Hence, -22.5cm is the focal length of the concave mirror.

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