A) 10 cm
B) 5 cm
C) 20 cm
D) 40 cm
Correct Answer: B
Solution :
The situation is as shown in the figure below : For plane mirror\[,\]\[v=u\]. So, the image will be formed at a distance of\[12\,\,cm\]from the plane mirror. This image is therefore at a distance of\[24\,\,cm\]from the object. Distance between the object and the convex mirror is\[20\,\,cm\]. So the distance between the pole of convex mirror and the image is\[24-20=4\,\,cm\]. Being on the right side of the convex mirror this image distance will be taken as positive. So, for the convex mirror\[u=-20\,\,cm\]and\[v=+4\,\,cm\] \[\therefore \] \[\frac{1}{f}=\frac{1}{v}+\frac{1}{u}=\frac{1}{4}-\frac{1}{20}=\frac{4}{20}\mathbf{=}\frac{\mathbf{1}}{\mathbf{5}}\]You need to login to perform this action.
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