When we talk about the flow of electricity, we are specifically referring to **current**.

Current is the rate at which electrons flow through a circuit. With a voltage applied to a circuit, the current will flow through the conductive loop and load. We can measure current in units of Amperes or amps (A).

Current also comes in two forms, Direct Current (DC) and Alternating Current (AC). Direct current refers to the flow of electricity in one direction. Alternating Current is the flow of electricity that periodically reverses direction. In this lesson, we will cover direct current.

If we go back to the water analogy and look at electricity as a water tank with a pipe attached below it, we can think of current as the flow of water through the pipe.

Many things can affect the flow, such as the water pressure (voltage). A higher volume of water will increase the pressure (voltage) in the tank and result in an increase in flow (current) through the pipe.

With all elements in a circuit staying the same, a higher voltage will result in a higher current will flow, while a lower voltage will result in less current.

A simple way to control the current in a circuit is a push button.

The schematic has 2 lines with circles at the ends which represent the conductive path. When the top portion of the schematic is not touching the circles, the circuit is open and there is no current.

When the top pad is touching the circles, the circuit is closed and there is current. The closed-circuit button is represented by the schematic below.

### Instructions

Use the arrows to observe the effect of the water level and pressure on the water flow through the pipe.

Move to the next exercise when you are ready.