Question

Why do we use mercury in thermometers? Can water be used instead of mercury?

Answer 1

Mercury is used in thermometers because:

• Its expansion is uniform.
• It is opaque and shining.
• It does not stick to the sides of the glass tube.
• It is a good conductor of heat.
• It is easily available in pure state.

Water cannot be used instead of mercury, because of the following reasons:

• Water cannot expand as much as mercury expands for a small rise in temperature.
• Water is not opaque and shining.
• Water sticks to the sides of the glass tube.