A) 15cm
B) -15cm
C) 10cm
D) zero
Correct Answer: B
Solution :
Given \[u=-30\] cm and \[v=-10\] cm \[\frac{1}{f}=\frac{1}{v}-\frac{1}{u}\] \[=\frac{1}{-10}-\frac{1}{-30}=-\frac{2}{30}\] \[\frac{1}{f}=-\frac{1}{15}\] \[f=-15\,cm\] Minus sign signifies that lens used is concave.You need to login to perform this action.
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