A Numerical from Combination of thin lenses in contact

Two thin lenses of focal lengths f1=20cm and f2=60cm are placed in contact. find the focal length f3 of the combined lenses. find also the focal length f of a third lens placed in contact with these two that would result in overall focal length f11=-40cm. (Asked Young) Incoming search terms:class 9 science sample paper for [...]

Why can’t we see through opaque objects?

Why can’t we see through opaque objects? What is the reason? (Kavya asked) Answer: When light falls on an object, a part of it is absorbed, another part transmitted and the rest reflected. Surfaces have different abilities for these. Substances which do not transmit any light are opaque. Incoming search terms:what are the possibilities of [...]

What accounts for the acceleration or deceleration of light when it travels from one medium to another?

“When light passes through different mediums speed changes but who provide acceleration to change velocity?” This question was posted by Jishnu Answer: Just imagine you are participating in a cross country race. When the road is good you can travel faster; but if the path is a marshy place, your speed will decrease. This is ...Read the full post