Power of  a  lens is 0.4  D. what is its focal length? 

Asked by jatin452002 | 8th Jun, 2017, 06:40: PM

Expert Answer:

If the Power (P) of a lens is 0.4  D,
The focal length (f) of the lense is given by the following relation:
begin mathsize 12px style straight P equals 1 over calligraphic f
0.4 equals 1 over calligraphic f
calligraphic f equals fraction numerator 1 over denominator 0.4 end fraction equals 2.5 space straight m equals 250 space cm end style
Therefore the focal length of the given lense is 250 cm.

Answered by Abhijeet Mishra | 9th Jun, 2017, 09:59: AM

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