Question

Two lenses of power-3.5 D and + 1D are placed in contact
Find the total power of the combination of lens. Calculate the
focal length of this combination.​

Answer 1

Answer:

power = pa +pb

a = -3.5 D

b = +1 D

pa + pb

-3. 5 +1

= -2.5D

Now finding focal length,

p = 1/f

-2.5 = 1/f

f= 2.5×1

=2.5m.