ABSTRACT
Mole (mol) A mole is the number of unitary particles (these must be specified, e.g. atoms, ions, molecules) as there are atoms in 0.012 kg (12 g) of carbon-12
Luminosity Candela (cd) This is derived from comparison with the luminous intensity emitted from the body of freezing platinum under specified conditions
Pico 10-12 p Picofarads, a measurement of capacitance
Nano 10-9 n Nanomoles, a number of hydrogen ions
Micro 10-6 µ Micrograms, drug dose
Milli 10-3 m Milliamps, current to cause ventricular fibrillation
Kilo 103 k Kilopascals, pressure
Mega 106 M Megawatts, the power from an electricity generator
Giga 109 G Gigabytes, as in computer memory
Energy can be considered as stored work. Potential energy can be stored in many forms, e.g. a wound-up spring, a kilogram of carbohydrate, a pressurized cylinder, a battery, a tank full of hot water. No matter how the energy is stored or converted from one form to another, the units used are the same and equivalent, i.e. joules. Potential energy is usually easily converted into kinetic energy, e.g. free-wheeling a bicycle down a hill or opening a cylinder of gas.
