Question

You had a convex lens of focal length 5m, and two
lenses A and B of unknown focal lengths. You
observed that if you placed lens A in contact with the
convex lens, the combination acted like a plane glass
slab. On the other hand, if lens B was kept in contact
with the convex lens, the combination acted like a
convex lens of focal length 10 cm WHAT IS POWER OF LENS B?

Answer 1

Answer:

power of lens= 1d is correct

Answer 2

Answer:

Power of lens B is 1dioptre

Explanation:

let the given convex lens be C lens

now, according to question

$F_{C}$ + $F_{B}$ = $F_{BC}$

5 + $F_{B}$ = 10

$F_{B}$ = 5m

we know,    p = 1/f

$P_{B}$ = 1/5

$P_{B}$ = 0.2 dioptre