Question #bfd7d

WE know that a convex lens forms a virtual and erect image when the object is kept between the optical center and the principal focus of the convex lens.

http://![https://www.google.co.in/imgres?imgurl=http%3A%2F%2Fwww.leydenscience.org%2Fphysics%2Felectmag%2Fcon_inf.jpg&imgrefurl=http%3A%2F%2Fwww.leydenscience.org%2Fphysics%2Felectmag%2Fimage_des.htm&docid=9gvnGwATT0RfRM&tbnid=IqtlPFkWs9WsVM%3A&vet=1&w=405&h=197&bih=589&biw=1366&q=virtual%20image%20formed%20by%20convex%20lens&ved=0ahUKEwitn6rv9-TRAhWLuY8KHbHiANIQMwgeKAMwAw&iact=mrc&uact=8]()

THIS virtual image is much larger than that of the object and hence the magnification ,#m >+1#.

MORE over when the object is at focus then the image formed at infinity is larger than the object ,i.e a magnified image is formed and

#m> +1#
.

More over if the object is also between C and F then also a magnified image is formed.

SINCE ALL THESE CAPABILITIES ARE NOT PERSUADED BY OTHER LENSES ,i.eCONCAVE LENS ,HENCE ONLY CONVEX LENS IS USED IN A MAGNIFIER.