Question

In the adjoining diagram, distance between two lenses will be ($F_1$ and $F_2$ are focal length of two lenses)

• A. $F_1$
• B. $F_2$
• C. $F_1+F_2$
• D. $F_1-F_2$

Answer 1

The correct option is C $F_1+F_2$

$\begin{array}{c}\text{As the rays are coming parallel to}\\ \text{the principle axis inf}{L}_1\text{, so it}\\ \text{will converge at the focus of Lens}\\ \text{Li, i.e. F.}\\ \text{And, these converging ray at}{F}_1\\ \text{become pallalel to the principle}\\ \text{axis of Lens}{L}_2\text{.}\end{array}$

And we xnow that if a ray

pass through the focus of the

lens, then it become parallel

to the principle axis of the lens.

so, converging point of ray must

be $F_2$ distance (focaldistance) from

the $L_2$. Distance between lenses $\left(L_1\&L_2\right)$

$=F_1+F_2$