Question

Two convex lens of equal focal length f are placed in contact the resultant focal length of combination will be

Answer 1

Power of lens = 1/focal length = 1/f

If there is a combination of lens, then we can write

power of combination = p1 + p2

P = p1 + p2

1/F = 1/f + 1/f (∵convex lenses have same focal lengths )

1/F = 2/f

F= f/2

Focal length of combination = F = f/2

Answer 2

Answer:

if two convex lenses having equal focal lens are kept in contact with each other than resultant focal length becomes half