Question

a hollow prism filled with water shows more or less bending as compared to a solid glass prism. explain

Answer 1

No....Dispersion doesn't occur ,since medium 1 and 2 are same ..and hence they have same refractive index.

Moreover the speed of all the wavelengths is same in vacuum (or air),hence they travel as a single beam. But the speed of different wavelengths is different in glass (media),the refractive index depends on the wavelength and hence a spectrum is seen . If the hollow prism is filled by some other media ,there will be a chance of spectrum formation ,depending on media.The variation of refractive index with wavelength may be pronounced in some media than the other.

hope this helps you.....:)

@skb

Answer 2

Dispersion happens when the light trespasses the boundary between water and air because refractive index of substances depend slightly of the light color (wavelength). In case of hollow prism immersed in water light still trespasses boundaries between water and air, so there will be dispersion.
Hope this will help you.