Question

Two coaxial diverging lenses are kept as shown in figure. An object $O$ is placed , then the final image formed will be

• A. Virtual or real depends on $d_1$ and $d_2$ and also on the focal lengths of the lens
• B. Virtual or real depends on $d_1$ and $d_2$ only
• C. Real for any value of $d_1$ and $d_2$
• D. Virtual for any value of $d_1$ and $d_2$

Answer 1

The correct option is D Virtual for any value of $d_1$ and $d_2$

Effective focal length of combination is
$\frac{1}{F}=\frac{1}{f_1}+\frac{1}{f_2}-\frac{d}{f_1{f}_2}$
$f_1$ and $f_2$ both are negative.
Hence, $F$ is also negative.
As, object is real, combined lens has negative focal length, hence image is always virtual.
Hence , the correct answer is option (a)