Learning Objectives n n To learn the difference

Learning Objectives n n To learn the difference between static and current electricity To build a circuit

Current Electricity n Refers to the movement of electrons through a conductor in a controlled fashion

Static vs Current Electricity Static Electricity Type of electron movement Path of electrons Duration of flow Usefulness Random Unpredictable Short Stationery objects Current Electricity Steady in a given direction Can be directed Long Can power appliances

Electric Circuits n n n To make any electrical device operate a continuous flow of electrons is required The continual flow of electrons is called an electric circuit What do we need to complete a circuit?

1. Energy Source n As small as a battery… n as large as a generating station

2. The Load n n Any device which converts electrical energy to another form of energy In other words, anything that runs on electricity

3. Connecting Wires n n Joins all the parts of the circuit together Allow the source and the load to be far apart Made of good conducting material Provide a controlled path for electrons

4. The Switch n n Optional Controls electron flow ‘On’ = closed circuit and electrons flow ‘Off’ = open circuit and flow is stopped

Closed circuit – Switch is ‘on’

Open circuit – Switch is ‘off’

Circuit Symbols Sources of electrical energy: + Single battery Three batteries

Electrical Conductor: (always draw 90 o corners, and straight lines) Control Device: Open Switch Closed Switch

Loads:

Loads, cont’d: Ohmmeter

Why do we use circuit diagrams? n So this……. Becomes this!

Series Circuits n n Electrons have only one path to follow Loads are all connected one after the other (i. e. in series) If any part of the circuit is broken, none of the loads will work Ex: if one light bulb burns out, none will light up

n How would you draw a circuit diagram for 3 lamps connected in series, with a switch and one electric cell? n Draw a circuit diagram with a three-cell battery in series with a switch and 2 lamps.

Parallel Circuits n n n Electrons have two or more paths to follow Loads are all connected by branches One faulty load will not affect the others Ex: if one light bulb burns out, the others will continue to work In your home, parallel circuits separate smaller series circuits

n How would you draw a circuit showing a twocell battery with three lamps connected in parallel, and a switch for each lamp? n Draw a circuit diagram showing a two-cell battery, two lamps, and one motor. The loads are connected in parallel.

Practice! n Page 436 # 1 - 5