Q. 183.8( 10 Votes )

# 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?

Answer :

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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PREVIOUSAn object is placed at a distance of 15 cm from a convex lens of focal length 20 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.NEXTA concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object from the lens ? Draw the ray diagram.

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