Question

The focal length of a convex lens is 50 cm. what is its power?
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Answer 1

Answer:

convex ( so focal length is positive )

given : f = 50cm or +50×10^-2m

so find p =?

formula p =1/f

p = 1/50×10^-2

p= 100/50

P = 2

so your final answer is 2

Answer 2

Given,

• The focal length of a convex lens 'f' = 50 cm

To find,

• We have to find the power of the convex lens whose focal length is 50 cm.

Solution,

We can simply find the power of the convex lens by using the following formula:

          Power of the convex lens = 1/f (in meter)     (*)

The focal length of a convex lens 'f' = 50 cm

The power of the convex lens is defined as the reciprocal of the focal length of a lens in meters.

The focal length of the convex lens in meters = 50/100

                                                                             = 1/2 meters        

         Using (*), we get

Power of the convex lens = 1/1/2

                                           = +2 D

Hence, the focal length of a convex lens is 50 cm, then the power of the lens is +2D.