Question

A lens when immersed in a trAnsparent liquid becomes invisible. Under what condition does it happen?

Answer 1

when a lens is immersed in a transparent liquid , it becomes invisible. this statement can also be said as " when a lens is immersed in a transparent liquid, lens doesn't follow law of refraction. "

when the refractive index of liquid equals refractive index of lens , lens becomes invisible because velocity of light doesn't affect after then.

hence, the condition is " refractive index of liquid should be refractive index of lens "