Question

Doctor advise 4D lens. what is focal length

Answer 1

P=1/f
4= 1/ f
f=1 / 4
f =0.25

the focal length of the lens is 0.25 cm

Answer 2

$\huge \boxed{hey \: mate}$

$\huge \mathfrak \pink{answer - }$

p=4d

p=1/f

4=1/f

f=1/4

f=0.25

$\huge{hope \: it \: helps \: u}$