A) 30 cm
B) 15 cm
C) 5 cm
D) 10 cm
Correct Answer: B
Solution :
Given \[m=\frac{\upsilon }{u}=2\] or \[\upsilon =2u\] For real image, u is negative and \[\upsilon \] is positive, from formula \[\frac{1}{f}=\frac{1}{\upsilon }-\frac{1}{u}\] or \[\frac{1}{f}=\frac{1}{\upsilon }-\frac{1}{-\upsilon }=\frac{1}{\upsilon }+\frac{1}{u}\] or \[\frac{1}{10}=\frac{1}{2u}+\frac{1}{u}=\frac{3}{2u}\] Hence, \[u=\frac{30}{2}=15cm\]You need to login to perform this action.
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