TWO COAXIAL THIN LENSES OF EQUAL AND OPPOSITE FOCAL LENGTHS ARE SEPARATED BY A DISTANCE d. THE COMBINATION WILL BEHAVE LIKE A
1.CONVEX LENS
2.CONCAVE LEN
3.PLANE GLASS PLATE
4.PLANE MIRROR
Focal length of combination of lens is given by . Hefe f1=-f2, so putting this value we get
.
Hence the focal lengths are positive, hence the combination will behave like a concave lens.
.
Hence the focal lengths are positive, hence the combination will behave like a concave lens.