Electrical Engineering ⇒ Topic : Simple electrical circuit

SIMPLE ELECTRIC CIRCUITS

When two unequal charges having a potential difference between them are connected by a conductor, current will flow from the positive charge to the negative charge.

An electric circuit is a complete conducting path starting at one end of the voltage source and ending at its other end. It consists of the voltage source, the conductor and other circuit elements. An example of electric circuit is a lamp connected by conductors across a battery (dry cell), as shown in Fig. (1). Current flows from the positive terminal (+) of the battery through the lamp to the negative (-) battery terminal, and continues by going through the battery from the negative to the positive terminal. As long as this path (circuit) is not broken, it is a closed circuit and current will flow (Fig. 1 (a)). However, if the circuit is broken at any point (Fig. 1. (b)), the circuit is an open circuit and no current flows. Current flow in the external circuit is due to the movement of electrons in the opposite direction as indicated by arrows in Fig. 1 (a).

    A simple electrical circuit normally consists of a conductor and a voltage source,both connected in a series loop. The physical path of the current flow is actually the electric circuit, in which the voltage source, the connecting wires (conductors),current and resistance are present. The resistance of the circuit controls the amount of current flow in the circuit. By knowing any two of the three quantities (voltage, resistance and current), the third may be determined. This is done mathematically by using Ohm's Law.

                                                       figure (1)