If a spherical lens has a power of, – 0.25 D, the focal length of this lens will be *

Asked by adipadmakarri | 19th Aug, 2020, 09:01: AM

Expert Answer:

P o w e r space o f space l e n s comma space P space equals space minus space 0.25 space D
P equals space fraction numerator 1 over denominator f left parenthesis i n space m e t r e s right parenthesis end fraction
f space equals space 1 over P space equals space fraction numerator 1 over denominator negative 0.25 end fraction space equals space fraction numerator 100 over denominator negative 25 end fraction space equals space minus 4 space m space
T h u s comma space f o c a l space l e n g t h space i s space 4 space m space
 
Negative sign of focal length indicates that it is concave lens. 

Answered by Shiwani Sawant | 19th Aug, 2020, 11:24: AM