A) 60 cm
B) 20 cm
C) 40cm
D) 30cm
Correct Answer: D
Solution :
Given, \[R=2f=40\text{ }cm.\] \[\therefore \] \[f=20cm\] \[m=2\] \[m=\frac{v}{u}=2\] \[\therefore \] \[v=2u\] Using mirror formula, \[\frac{1}{f}=\frac{1}{v}+\frac{1}{u}\] \[\frac{1}{20}=\frac{1}{2u}+\frac{1}{u}=\frac{1+2}{2u}\] \[u=30cm\]You need to login to perform this action.
You will be redirected in
3 sec