1. 2.4

2.  A practical way to describe a circuit is to draw a circuit diagram  Uses standard symbols to represent the components and their connections

3. SYMBOLCOMPONENTSYMBOLCOMPONENT Connecting wireCell SwitchBattery

4. SYMBOLCOMPONENTSYMBOLCOMPONENT ResistorVoltmeter BulbAmmeter

5.  Draw a simple circuit (using symbols) that includes:  2 cells  A switch  A resistor  A light bulb

7.  There are essentially 2 types of circuits:  Series  Parallel

8.  Only 1 pathway for current to flow  Simple  Electrons only have one path to follow  Each electron must go through each load, in turn  Current (I) is the same at each point in the circuit

9.  More than 1 pathway for current to flow  Charges flow around 2 or more different “loops”  Current is not the same at all points  Some electrons will take one path and others will take a different path  Most circuits are a combination of series and parallel

10.  Ammeter measures current (in amperes, A) at a particular location in the circuit  Where the ammeter is located!  Ammeter is always connected in series

11.  Voltmeter measures potential difference (in volts, V) between 2 points  Electric potential on one side of a load, such as a bulb or resistor, is greater than the electric potential on the other side  Voltmeter measures this difference  Always connected in parallel

12.  What if one of the bulbs was burnt out?  Bulbs must be connected in parallel  How do we turn the lights on?  1 switch  Power source and switch must be connected in series

13.  The current is the same at all points in a series circuit  I T = I 1 = I 2 = I 3 …

14.  Loads transform electrical energy into other forms of energy  The total energy transformed must equal the work that is done by the cell (power source) .: The potential difference of the cell must equal the sum of the potential differences of each load

15.  V T = V 1 + V 2 + V 3 …

16.  The total resistance of the circuit will increase as more loads are added in series  R T = R 1 + R 2 + R 3 …  What would happen if we added more loads (i.e. light bulbs) in series?

17.  There is more than one path for electrons to flow  The current entering a parallel connection divides  The sum of the currents through each path equals the total current  I T = I 1 + I 2 + I 3 …

18.  Voltage is the same across all loads in the circuit  Equivalent to the potential difference across the cell  V T = V 1 = V 2 = V 3 …

19.  The total resistance of loads connected in parallel, is less than the resistance of any of the loads individually  R T < R 1 ; R T < R 2 ; R T < R 3 ; …