Power of lens: The degree of convetgence or divergence of light rays that can achevied by a lens is expressed in terms of its power. The reciprocal of focal length is power of lens. Powe of lens P = 1/f( in m). P= 100/f (in cm). The unit of power of lens is dioptre. Denoted by D. NOW FINDING FOCAL LENGTH WHEN POWER OF LENTHVIS GIVEN. Example: doctor advised to use 2D lens. Find focal length. Sol: using, p = 100/f ( in cm); 2=100/f. Therefore, f= 100/2 =50 cm. The lens has focal length , f= 50 cm
6 4 6
Yes ,But we can give it in simple way.THANKS
Plz.. mark it as best if u admit it..

This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Power(P) = 1/Focal length(f) 

so Power is the reciprocal of the focal length of the lens

so you take out the Focal length

P = 1/f
f = 1/P

the unit is in metres

3 4 3