Electrical Circuits

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Slide 1

S.MORRIS 2006

ELECTRICAL CIRCUITS

Slide 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 round a circuit.

Slide 3

What is an electric current?

An electric current is a flow of microscopic particles called electrons flowing through wires and components.

+

-

In which direction does the current flow?

from the Negative terminal to the Positive terminal of a cell.

Slide 4

Simple circuits

Here is a simple electric circuit. It has a cell, a lamp and a switch.

To make the circuit, these components are connected together with metal connecting wires.

cell

lamp

switch

wires

Slide 5

simple circuits

When the switch is closed, the lamp lights up. This is because there is a continuous path of metal for the electric current to flow around.

If there were any breaks in the circuit, the current could not flow.

Slide 6

Circuit diagram

cell

switch

lamp

wires

Scientists usually draw electric circuits using symbols;

Slide 7

circuit diagrams

In circuit diagrams components are represented by the following symbols;

cell

battery

switch

lamp

motor

ammeter

voltmeter

buzzer

resistor

variable resistor

Slide 8

Types of circuit

There are two types of electrical circuits;

SERIES CIRCUITS

PARALLEL CIRCUITS

Slide 9

Series circuits

The components are connected end-to-end, one after the other.

They make a simple loop for the current to flow round.

If one bulb ‘blows’ it breaks the whole circuit and all the bulbs go out.

Slide 10

Parallel circuits

The current has a choice of routes.

The components are connected side by side.

If one bulb ‘blows’ there is still be a complete circuit to the other bulb so it stays alight.

Slide 11

Measuring current