THE VOCABULARY
Instruments, concepts, and phenomena — the shared vocabulary of the site.
Ampere
The SI base unit of electric current. Since 2019, defined as the flow of exactly 1/(1.602176634 × 10⁻¹⁹) elementary charges per second. Symbol: A.
Boltzmann constant (k_B)
The conversion factor between temperature and energy, k_B = 1.380649 × 10⁻²³ J/K.
Calorie
A thermal unit of energy — the heat needed to raise one gram of water by one degree Celsius — equal to 4.186 joules.
Coulomb (unit)
The SI unit of electric charge. One coulomb equals the charge carried by 6.24 × 10¹⁸ protons, or the charge that flows past a point in one second when the current is one ampere.
Farad
The SI unit of capacitance. One farad holds one coulomb of charge per volt of potential difference. Symbol: F.
Henry
The SI unit of inductance. One henry is the inductance of a coil in which a current changing at one ampere per second induces an EMF of one volt. Symbol: H. 1 H = 1 V·s/A.
Joule
The SI unit of energy — one newton acting through one metre — named for James Prescott Joule.
Pascal
The SI unit of pressure: 1 Pa = 1 N/m². Named for Blaise Pascal.
Tesla
The SI unit of magnetic flux density. One tesla equals one weber per square metre, or one newton per ampere-metre. Symbol: T.
Volt
The SI unit of electric potential difference. One volt equals one joule of work per coulomb of charge transported. Symbol: V.
Weber
The SI unit of magnetic flux. One weber is the flux through a one-square-metre area of a one-tesla field. Symbol: Wb.