A) 5.5cm
B) 7.5cm
C) 12.0 cm
D) 20.0 cm
Correct Answer: B
Solution :
Key Idea: The converging point in the figure acts as virtual object. As shown in figure, the point on the right side of the lens of which rays converge will behave as virtual object at the lens. \[\therefore \] \[u=+12\text{ }cm,\text{ }f=20\text{ }cm\] From lens formula, \[\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\] \[\therefore \] \[\frac{1}{20}=\frac{1}{v}-\frac{1}{12}\] Or \[\frac{1}{v}=\frac{1}{20}+\frac{1}{12}=\frac{3+5}{60}=\frac{8}{60}\] Or \[u=\frac{60}{8}=7.5\,cm\] So, image will be formed on same side of the virtual object at a distance of 7.5 cm from the lens.
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