Question

In fire polishing of glass why the glass is heated to make the sharp edges smooth? How by supplying energy the sharp edges are bcomin smooth?

Answer 1

Dear Student,
The fire polishing technique is used to make the rough glass surface smooth by heating. Glass is an amorphous substance It does'nt have a sharp melting point .It melts over a range of temperature.
Glass becomes smooth on heating because of the property of surface tension .When heat is supplied to the glass it starts melting slowly and and changes to the melted state ,this state has a surface tension and tends to acquire minimum surface area to reduce this tension. Therefore the melted glass acquires spherical shape and on cooling becomes smooth rounded surface.
Regards!