At the point of incidence where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror. This line is known as a normal line (labeled N in the diagram). The normal line divides the angle between the incident ray and the reflected ray into two equal angles. The angle between the incident ray and the normal is known as the angle of incidence. The angle between the reflected ray and the normal is known as the angle of reflection.
Even if the water were to be cooled from the bottom, the coldest water would float to the top and when the whole pond became 0Â°C the ice would float to the top as it formed. In some cases where rocks are below the freezing point (exposed to the air part of the time, ice can form and stick to the rocks under water.
a physical change. because the water is still water just the appearance of it has changed. It is also known as a phase change because the boiling is just a phase once it is off the heat it will be normal water and if you freeze it it will become ice, but once you leave it out again its just water.