AQA A-Level Physics/Charge and Current

Current, measured using an ammeter, is the rate of flow of charge in a given part of a circuit. It is split between branches in parallel circuits in accordance with the resistance in the branches and Ohm's law (which states that Voltage across a component is equal to the resistance of the component multiplied by the current traveling through it (In symbols, V=IR).

UnitsEdit

  • Current: Has the unit of the Ampere (A), usually referred to by the diminutive form of "Amp(s)". Note that despite the fact that current is usually given as being the rate of flow of charge, the Ampere is one of the seven SI Base Units, the other 6 being the metre(length), the second (time), the kilogram (mass), the Kelvin (temperature), the mole (amount of substance) and the candela (luminous intensity).
  • Charge: The Coloumb(C), named after Charles-Augustine de Coulomb. In base units, the Ampere-second (As). It is also the charge carried by 6.2415093414 ×1018 electrons.