To use a model to represent electricity Wednesday, February 10, 2016

 The circuit diagram shows a series circuit with a motor and a lamp  It shows 3 positions where the ammeter was connected (with values shown)  What do you notice about the current? A A A M 1.2A  Current remains the same – 1.2A leaves the battery, and 1.2A returns  Each component in series receives the same current (1.2A)

 Electricity is a difficult topic to explain because you cannot see it!  To help explain electricity we can use a model – a model uses things we understand that work in a similar way to the things we don’t understand  Look at the power station model of electricity – stick it into your book and answer the questions

 Battery – the coal mine  Bulb(s) – the power station  Electric wires – the tracks  Electrons – the coal trucks  Current (flow of electrons) – number of coal trucks  Voltage (push provided) – how much coal the trucks contain and the push they are given around the circuit  Switch – workmen who can break or mend the tracks

 If another bulb is added the current is reduced – the coal trucks give half their coal to one power station, and give the other half to the second power station  If another bulb is added the voltage changes, depending on the resistance of the bulb – e.g. one power station might take lots of the truck’s coal (high resistance) leaving just a small amount of coal for the other power station (lower resistance)  Model not perfect – only describes series circuits / electrons don’t really flow around (only their charge passes) etc…

 Your task is to come up with your own model for electricity in a series and parallel circuit  Think about how you will represent the cell / switch /bulb / wires  How will you model current and voltage?  E.g. you could do the number of people entering a football stadium to watch Arsenal - people represent electrons; the ticket they carry could be the energy which they transfer at the gate; the people always go home and then get a new ticket etc…