A card sheet divided into squares each of size 1mm2 is being viewed at a distance of 9cm through a magnifying glass (a converging lens of focal length 9cm) held close to the eye and the magnifying glass if the virtual image of each square is to have an area of 6.25mm2. Would you be able to see the squares distinctly with your eyes very close to the magnifier?
Area of virtual image A=6.25mm2
Ao=1mm2
Linear magnification m=√A/Ao=2.5
But m=v/u⇒v=2.5u
also, f=10cm
1v−1u=1f
so, v=−15 cm; u=−6 cm
Virtual image is formed at 15cm which is less than 25cm. Hence, it can not be seen.