A) Convex, 12 cm
B) Concave, 12 cm
C) Convex, 6 cm
D) Convex, 18 cm
Correct Answer: C
Solution :
\[m=-\frac{v}{u}=-3\]or \[v=3u\] [\[\therefore \]The image is real the combination is convex] Now, u = 10 cm, therefore v = 30 cm. If F is the focal length of the combination, \[\frac{1}{F}=\frac{1}{v}+\frac{1}{u}=\frac{1}{30}+\frac{1}{10}\]or \[1=15/2\,cm.\] Again from ?\[\frac{1}{F}=\frac{1}{{{f}_{1}}}+\frac{1}{{{f}_{2}}}\] we get \[{{f}_{2}}=6\,cm.\] Hence, the correction option is [c].You need to login to perform this action.
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