Electric current is one of the seven fundamental physical quantities in science. To properly measure how much electricity is flowing through a wire, we must define its standard unit.
The unit is named after André-Marie Ampère, a French physicist who was one of the main discoverers of electromagnetism.
Current is measured using a device called an Ammeter, which is always connected in series in an electrical circuit.
The standard SI unit for measuring electric current is the Ampere (A), often casually referred to as 'Amps'.
Current ($I$) is defined as the rate of flow of electric charge ($Q$) over time ($t$). Formula: $I = \frac{Q}{t}$
Therefore, we define 1 Ampere as: "1 Ampere of current is said to flow through a conductor when 1 Coulomb of electric charge passes through its cross-section in 1 second."
Mathematically: $1 \text{ Ampere} = \frac{1 \text{ Coulomb}}{1 \text{ Second}}$
Since 1 Coulomb of charge consists of approximately $6.24 \times 10^{18}$ electrons, a current of 1 Ampere means that more than 6 billion billion electrons are flowing past a specific point in the wire every single second.
For smaller electronics (like mobile phones), we use milliamperes (mA), where $1 \text{ mA} = 10^{-3} \text{ A}$, or microamperes ($\mu A$), where $1 \mu A = 10^{-6} \text{ A}$.
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