If there is a crack in the glass window, why does that place look shiny?

If there is a crack in the glass window, why does that place look shiny?

Answer: If there is a crack in the glass window, the area looks shiny. Because there is air in the cracks. Rays of light incident from the dense medium of glass to the thin medium of air at an angle greater than the critical angle of the glass and because of this, the rays of light are totally reflected. As a result, the cracked area looks brighter.