A) 10 cm
B) 30 cm
C) 15 cm
D) 20 cm
Correct Answer: D
Solution :
[d] \[m=-\frac{v}{u}-\left( \frac{f}{u-f} \right)\] \[\text{Now }{{\text{m}}_{1}}=-\left( \frac{f}{25-f} \right)\] ??(i) \[\text{and }{{m}_{2}}=-\left( \frac{f}{40-f} \right)\] ??(ii) \[\therefore \frac{{{m}_{1}}}{{{m}_{2}}}=\frac{40-f}{25-f}\text{ or }4=\frac{40-f}{25-f}\text{ or f=20}\,\text{cm}\text{.}\]You need to login to perform this action.
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