Question

Two lens of focal length f1 and f2 are kept in contact coaxially.
The resultant power of combination will be
(a)f₁f₂/f₁ - c
(b)f₁ + f₂/f₁f₂
(c ) f₁ + f₂ (d)f₁/f₂ - f₂/f₁​

Answer 1

(B)

IS YOUR ANSWER

REFER TO THE ATTACHMENT

THANK YOU :(

Answer 2

Answer:

When two lenses are placed coaxially then their equivalent focal length F is given as

$\frac{1}{ f_{1} } = \frac{1}{ f_{1} + f_{2} } \to \: f = \frac{ f_{1} f_{2} }{ f_{1} + f_{2}}$

Now power=

$\frac{1}{ \sf{focal \: length}} \\ \\ = \frac{ f_{1} + f_{2} }{ f_{1} f_{2} }$

Hence option C is correct.

Hope it helps you from my side

How Was Your Exam?