Question

what is the focal length of a concave lens. when radius is 54???​

Answer 1

Answer:

radius of curvature of a concave lens is negative because it lies on the same side of the lens. Radius is double of focal length.

• R = 2f

According to the question, we are asked to find the focal length of a concave mirror whose radius of curvature is 54cm

⇒ - 54 = 2f

⇒ f = -54/2

∴ f = -27 cm

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