---
tags:
  - electricity
  - electronics
---

# Circuits

An electrical circuit is a set of electrical components connected in such a way
that current flows in a loop from a voltage source, through the circuit elements
and back to the voltage source.

Below is a basic circuit representing a 9-volt
[battery](Cells_and_batteries.md#cells-and-batteries)
with a 10,000$\Omega$
[resistor](Resistance.md) attached
accross its terminals. Through the application of
[Ohm's Law](Ohms_Law.md) we can
determine that the maximum current will be 0.9 miliamps.

![](/img/basic-circuit.png)

## Open and short circuits

A circuit with a break in its loop is called an **open circuit**. When a circuit
is open, no current flows. We can induce an open circuit through the use of a
switch component that closes and breaks the circuit when invoked.

A **short circuit** is a path in a circuit that allows current to flow with
little or no resistance. This is usually unintentional and results in excessive
current flowing through the circuit. A short circuit is the opposite to an open
circuit. With an open circuit there is an infinite resistance between the two
terminals.

## Vertical circuit diagrams

Sometimes circuits can be represented in a vertical manner rather than in an
actual circuit. This is done to simplify the representation. In this approach
current is represented as flowing in a straight line from the voltage source
(represented with a circle) to ground.

The circuit below is functionally identical to the previous circuit but
represented vertically:

![](/img/vertical-circuit.png)