Question

two lenses are combined together . if the power of one of the lenses is +5D and combined focal length is 0.4m.What is the power of the second lens​

Answer 1

-0.4D(maybe)

Step-by-step explanation:

combined focal length (f)= 0.4m

D1 = 5D

Then f1= 1/D1

= 1/5 = 0.2 m

1/f=1/f1+1/f2

1/0.4=1/0.2+1/f2

f2= -5/2

D2=1/f2= -0.4D