A) zero
B) \[5cm\]
C) \[10cm\]
D) \[9cm\]
Correct Answer: A
Solution :
If rays are parallel to principal axis, then rays will converge if equivalent focal length is positive i.e. \[\frac{1}{{{f}_{1}}}+\frac{1}{{{f}_{2}}}-\frac{d}{{{f}_{1}}{{f}_{2}}}>0\] \[\frac{1}{-10}+\frac{1}{20}-\frac{d}{(-10)\,(20)}>0\]You need to login to perform this action.
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