# Amateur Radio Manual/Direct and Alternating Current

Electric current is necessary for amateur radio equipment to work. However, different components of a radio setup use different "types" of current. Although the electrons are the same, the rate at which they flow is different. Electric current can be divided into two main categories: direct current and alternating current.

## Direct Current

Direct current can be defined as current that flows in only one direction. Although imprecise, this definition will suffice for now. This current is generated, for example, from a battery. Consider a resistor connected across a battery. The current only flows from the positive terminal, through the resistor, and into the negative terminal of the battery. Furthermore, the current does not change as a function of time.

In this circuit, a current of $\mathrm {I} ={\frac {\mathrm {E} }{\mathrm {R} }}={\frac {1}{2}}=0.5\mathrm {mA} .$  This current is constant and travels in the direction of the arrow. This battery provides direct current.

## Alternating Current

Alternating current can be defined as current which flows both forwards and backwards. This is the current that is found in the outlets in a house.