CBSE Class 10 Answered

The object seems to be raised because ray of light coming through denser medium to rarer medium bends away from the normal.

 

For example: - 

 

This is due to the refraction of light, when light travels from glass (denser medium) to air (rarer medium) as shown in figure.

 

Light ray AD starting from the object A placed at the bottom of glass block gets deviated along DE.

Hence for the eye it appears as the light ray is coming from B.

Hence the object appears to be at B which is at raised height.

 

apprent depth BC and real depth AC are related as, μ = AC / AB , where μ is refractive index of glass