An electric circuit is a collection of electrical devices, called circuit elements connected by conductors in a closed path (i.e., in a complete loop). Circuit elements include, source of electrical energy (e.g. battery), sink of electrical energy (e.g. light bulb), and switch to complete or break the circuit. Conductors (e.g., copper wires) are then used to connect them together.   Electrical Symbols Circuit diagrams are essential part of the study of current electricity and are often drawn symbolically. In circuit diagrams, various circuit elements are represented by standard electric symbols. Circuit Diagrams A simple circuit, with a cell (if a series of cells is used, it is called a battery) and a resistor or bulb. Circuit diagram showing the measurement of current in the circuit and potential difference across a circuit element (e.g. the resistor). An ammeter is used to measure the current flowing in the circuit and must be inserted in series with the circuit element as shown. A voltmeter measures the potential difference between two points in a circuit and must be connected in parallel to the circuit element as shown. Note that: An ideal ammeter has zero resistance so that when inserted into a circuit, it does … Continue reading →

A direct current (DC) is a flow of charges around a circuit in the same direction all the time. – Batteries supply DC and most appliances need DC to function.   Alternating current (AC) is a flow of charges around a circuit that reverses its direction at regular intervals, usually many times a second. – Household electrical power is supplied in the form of AC which usually needs to be rectified to DC before use.   Back To D.C. Circuits