ELECTRICAL CIRCUITS AND COMPONENT SYMBOLS 1

Some circuit symbols In circuit diagrams components are represented by the following symbols; cellbatteryswitchlamp motorammetervoltmeter buzzer resistor Circuit Breaker 2

The CELL The cell stores chemical energy and transfers it to electrical energy when a circuit is connected. When two or more cells are connected together we call this a Battery. The cells chemical energy is used up pushing a current around a circuit. 3

What is an electric current? An electric current is the flow of electrons through a circuit. + - In which direction does the current flow? from the Negative terminal to the Positive terminal of a cell. 4

simple circuits Here is a simple electric circuit. It has a cell, a lamp and a switch. To make the circuit, these parts are connected together with metal wires. cell light switch wires 5

simple circuits When the switch is closed, the circuit is complete, and the lamp lights up. This is because there is a continuous path for the electric current to flow around. If there were any breaks in the circuit, the current could not flow. 6

circuit diagram cellswitchlightwires Electrical drawings are usually drawn using symbols; 7

types of circuits There are two types of electrical circuits; SERIES CIRCUITSPARALLEL CIRCUITS 8

The components are connected end-to-end, one after the other. Electrons flow in only ONE path. SERIES CIRCUITS If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out. 9

PARALLEL CIRCUITS The current has a choice of routes (MANY paths). The components are connected side by side. If one bulb ‘blows’ there will still be a complete circuit to the other bulb so it stays lit. 10

11 All information researched on the following web sites. ric%20circuit&rls=com.microsoft:en- ca&oe=UTF- 8&startIndex=&startPage=1&gws_rd= cr&um=1&ie=UTF- 8&hl=en&tbm=isch&source=og&sa=N &tab=wi lec1/elecex.htm www. Teachingzone.org (Electricity awareness course pack for teachers produced by C2B Media LTD