Question

Why is glass better than fused silica as a prism construction material for a monochromator to be used in the region of $400$to $800\mathrm{nm}$?

Short answer

A glass is better than fused silica as a prism construction material for a monochromator to be used in the region of $400$to $800\mathrm{nm}$for visible radiation.

Step-by-step solution

Given information

Give the reason behind choosing glass instead of fused silica for prism construction material for monochromators used in $400\mathrm{nm}$ to $800\mathrm{nm}$ region.

Figure of glass prism.

As the UV has the wavelength of $200-400\mathrm{nm}$ and for visible light, the wavelength is $400-800\mathrm{nm}$. So the dispersion of glass prism in visible radiation is greater than the fused silica.