classical electromagnetism) Electric charge Electrometer is often used to reconfirm the phenomenon of contact electricity leading to triboelectric sequences. Torsion balance used by Coulomb to establish a relation between charges and force, see above. For the ranges of charge values see: Orders of magnitude (charge) Electric current (current of charge) Ammeter Clamp meter d'Arsonval galvanometer Galvanometer Voltage (electric potential difference) Oscilloscope allows quantifying time-dependent voltages Voltmeter Electric resistance, electrical conductance, and electrical conductivity Ohmmeter Time-domain reflectometer characterizes and locates faults in metallic cables by runtime measurements of electric signals. Wheatstone bridge Electric capacitance Capacitance meter Electric inductance Inductance meter Energy carried by electricity or electric energy Electricity meter Power carried by electricity (current of energy) Wattmeter Electric field (negative gradient of electric potential, voltage per length) Field mill Magnetic field See also the relevant section in the article about the magnetic field. Compass Hall effect sensor Magnetometer Proton magnetometer SQUID For the ranges of magnetic field see: Orders of magnitude (magnetic field) Combination instruments Multimeter, combines the functions of ammeter, voltmeter, and ohmmeter as a minimum. LCR meter, combines the functions of ohmmeter, capacitance meter, and inductance meter. Also called component bridge due to the bridge circuit method of measurement. Thermodynamics Temperature-related considerations dominate thermodynamics. There are two distinct thermal properties: A thermal potential — the temperature. For example: A glowing coal has a different thermal quality than a non-glowing one. And a substance-like property, — the entropy; for example: One glowing coal won't heat a pot of water, but a hundred will. Energy in thermodynamics is calculated by multiplying the thermal potential by the amount of entropy found at that potential: temperature times entropy. Entropy can be created by friction but not annihilated. Amount of substance (or mole number) A physical quantity introduced in chemistry; usually determined indirectly. If mass and substance type of the sample are known, then atomic- or molecular masses (taken from a periodic table, masses measured by mass spectrometry) give direct access to the value of the amount of substance. (See also Molar mass.) If specific molar values are given, then the amount of substance of a given sample may be determined by measuring volume, mass, or concentration. See also the subsection below about the measurement of the boiling point. Gas collecting tube gases Temperature Electromagnetic spectroscopy Galileo thermometer Gas thermometer principle: relation between temperature and volume or pressure of a gas (gas laws). Constant