Transcript File
Wednesday, April 6, 2016 To use a model to represent electricity 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? Current remains the same – 1.2A leaves the battery, and 1.2A returns Each component in series receives the same current (1.2A) 1.2A +- +- A A M A 1.2A 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…