Don't tease people having spectacles!
In a concave lens, object (real) distance and image distance = m.
If 4 of these lenses are placed very close to each other ( i.e. having negligible separation between them)
Find the power of the combination. (In dioptres)
The answer is -2.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
Using the lens formula,
f 1 = v 1 − u 1
f 1 = − 3 2 1 − − 1 1 = − 2 1
f = − 2 m .
Power of 1 lens = f 1 = − 0 . 5 D
Power of combination = 4 × − 0 . 5 = − 2 D