CIRCUITS AND CURRENT

The build up of stationary electric charges (positive and negative) on two different surfaces.

Caused by the TRANSFER of electrons from one place to another.

Recall Static Electricity

Current Electricity

The continuous flow of electrons in a closed circuit.

What is an Electric Circuit?

A circuit is a pathway for electricity to flow made up of four basic components.

Component #1: The Source

Function: Provides the circuit with electrical energy and

a supply of current (electrons).

one-celled battery

three-celled battery

AC power supply

Schematic Diagram

AC

Component #2: Conductors

Function – Wires/Wires Joined: Provides a path for current to flow. In

a perfect conductor no energy is lost. The current flows with no resistance.

Function – Ground Connection: The ground allows electrons to flow to

the ground or from the ground.

wire

wires joined

ground connection

Schematic Diagram

Component #3: Switch

Function – Open Switch: An open switch prevents current from

flowing in a circuit.

Function – Closed Switch:A closed switch allows current to flow.

Function – Fuse/Circuit Breaker: A fuse prevents a circuit from overloading

with too much current by opening the circuit before it over heats.

open switch

closed switch

fuse/circuit breaker

Schematic Diagram

A fuse is basically a current limiting electrical device, designed to destroy itself instead of the equipment they are connected to.

A circuit breaker is an electrical switch designed to protect an electrical circuit from damage caused by current overload or short circuit.

Its basic function is to interrupt the current flow.

Component #4: The Load

Any device that needs electrical energy to function.

The load is designed to take the electrical energy and converts it into the needed form of energy.

e.g. stove, fridge, toaster, light bulb

Light Bulb

Converts electrical energy into light energy.

Schematic Diagram

Resistor

A device added to a circuit to decrease the amount of current (electrons) flowing in the circuit per second.

Schematic Diagram

A Motor

Converts electrical energy in to mechanical or kinetic energy (movement).

Schematic Diagram M

Types of Energy

Light Energy (e.g. light bulb)

Heat Energy (e.g.stove, curling iron, toaster)

Mechanical or Kinetic Energy - Movement (e.g. blender, ceiling

fan)

Sound Energy ( e.g. i-pod, radio)