if a convex lens and a concave lens are kept one over other than will there be any change in the image?
Answers
Answer:
First, we must determine the power of each lens. This is done by finding the reciprocal of the focal length (which must be in meters) and the unit of power would be the Diopter. The sign of the focal length comes into play. Convex lenses have positive power and concave lenses have negative power.
It is then a question of adding the powers as an arithmetic sum. The reciprocal of the new power would then be the focal length of the combo of lenses.
If the absolute value of the focal lengths are equal, then the new combo would be a plate-parallel piece of glass.
In the following image (courtesy of hyperphysics), imagining the two lenses are touching, we get: New Power = + 5 + (-3.33) = + 1.67 D. The new focal length is 60 cm. The converging power of the convex lens is said to be “diluted”.