Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature the glass piece is not seen. (i) When is the glass piece not seen ? (ii) why is the light of a single colour used ?

Light of a single colour is passed through a liquid having a piece of

1.	Light of a single colour is passed through a liquid having a piece of glass suspended in it. On changing the temperature of liquid, at a particular temperature the glass piece is not seen. (i) When is the glass piece not seen ? (ii) why is the light of a single colour used ?
Answer» SOLUTION :(i) The glass piece is not seen when the refractive INDEX of liquid becomes equal to the refractive index of glass. (ii) Light of a single colour is used because the refractive index of a medium (glass or liquid) is DIFFERENT for the light of different COLOURS.