The rate at which charge flows is the electrical current. The SI unit for electrical current is the ampere, which is defined as one coulomb of charge passing through an area per second. Consider a flashlight with a switch, a bulb, a battery, and wires. The switch controls the circuit, while the wire provides a current path between the components. Schematic representations of circuits use standardized symbols and solid lines to represent the individual circuit components and connecting wires. The blub is represented as a circle with a loop inside, which indicates the filament. The switch is represented as two points with a conducting bar and the battery as a series of long and short lines. When the switch is closed, the flashlight turns on as there is a complete path for charge to flow from the battery's positive to negative terminal. The conventional current direction is always from the positive to negative terminal, while the electron flow is from the negative to positive terminal as electrons are negatively charged.