Q18 of 117 Page 10

A doctor has prescribed a corrective lens of power + 1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

The power of this lens is positive (with a plus sign), therefore, this is a convex lens or converging lens. Now,

Power, P = 


So, +1.5 = 


  ∴


⇒ f=


So, Focal length of lens, f = +66.7 cm.

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