Basic electricity:2.0 Simple Electric Circuit

2.0 Simple Electric Circuit

An electric circuit is a closed path consisting of active and passive elements all interconnected and the current flow is confined to the closed path. Figure below shows a typical cir­cuit consisting of one active and two passive elements. An active element is one which supplies energy to the circuit where as a passive element is one which receives energy and then this energy is converted into heat (resistor) or stores it in an electric (capacitor) or magnetic field (induc­tor).

An electric circuit

A fundamental relationship exists between current, voltage, and resistance. A simple electric circuit consists of a voltage source, some type of load, and a conductor to allow electrons to flow between the voltage source and the load. In the following circuit a battery provides the voltage source, electrical wire is used for the conductor, and a light provides the resistance. An additional component has been added to this circuit, a switch. There must be a complete path for current to flow. If the switch is open, the path is incomplete and the light will not illuminate. Closing the switch completes the path, allowing electrons to leave the negative terminal and flow through the light to the positive terminal.

An electrical circuit schematic

The following schematic is a representation of an electrical circuit, consisting of a battery, a resistor, a voltmeter and an ammeter. The ammeter, connected in series with the circuit, will show how much current flows in the circuit. The voltmeter, connected across the voltage source, will show the value of voltage supplied from the battery. Before an analysis can be made of a circuit, we need to understand Ohm's Law.