The calibration of a mercury thermometer intended for work of precision is best effected after it has been sealed. Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 1 Various The calibration of a slide-wire, however, is much less troublesome than that of a thermometer tube for several reasons.
Most everyone knows that we use proteins, carbohydrates and fats for energy. Calories are measurement of a unit of heat or food energy. For example, we can achieve four calories per gram of proteins and carbohydrates, and nine calories per gram from fats.
Visible light such as sunlight carries radiant energy, which is used in solar power generation. In physics, and in particular as measured by radiometry, radiant energy is the energy of electromagnetic and gravitational radiation. As energy, its SI unit is the joule (J). The quantity of radiant energy may be calculated by integrating radiant flux (or power) with respect to time. The symbol Qe is often used throughout literature to denote radiant energy (e for energetic, to avoid confusion with photometric quantities).