# Flowing Electricity: Current and Amperes (amps)

**Current** ($I$) is the "flow" of electricity, measured in amperes or "amps" ($A$). One amp is equal to one coulomb ($C$) passing a given point in a circuit per second ($s$), or $A = {C}/{s}$. **Coulombs** are the standard measure of electrical charge quantity (i.e. electrons or protons).

Current can be derived by Ohm's Law as $I = V/R$.

## Video: Current (Khan Academy)

## Direction of Current

**Conventional current** is current that "flows" in the direction that the positive charge travels and is usually what's meant when talking about "current" without specifying the type of current. Current flows in the direction that the negative charge travels is usually referred to more explicitly as **electron current**.

In electrical engineering, contentional current is used for calculations even though currents are typically generated through the flow of electrons rather than protons.

Current can also "flow" in both directions simultaneously, such as in salt water. When salt is dissolved in water it forms free-floating sodium ($Na^+$) and chlorine ($Cl^-$) ions which will both respond to electric force, moving in opposite directions.

## History

Amperes are named after André-Marie Ampèr, known for inventing the solenoid and electric telegraph.

## Deeper Knowledge on Current and Amperes

### Conductance and Siemens

The ability to conduct to current, measured in siemens

### Ohm's Law

A formula for determining voltage, current, and resistance

### Resistance and Ohms

Opposition to current, measured in ohms

### Watt's Law (Power Law)

A formula to define the relationship between power, voltage, and current (P=IV)

## Broader Topics Related to Current and Amperes

### Charge and Coulombs

How force is exerted in electromagnetic field, measured in coulombs

### Electrical Engineering

Build and deconstruct electrically powered devices

### Electricity

Energy that results from charged particles

### International System of Units (SI)

Formal terms and definitions of the metric system