P1a Topic 10 Internal Assessment

Diagram of Electric Motors Coil of Copper WireMagnet Split-Ring Commutator

Energy Transfers 1.List the energy transfers for the following machines. 2.Identify the useful energy output and the wasted energy output. a)Firework b)Battery-Operated Radio c)Electric Motor d)Light Bulb e)Hairdryer

Units of Measurement in Physics Voltage ( ) Current ( ) Resistance ( ) Power ( ) Charge ( ) Energy ( )

Physics Formulae Voltage = Current x Resistance –V = I x R Power = Current x Voltage –P = I x V Charge = Current x Time –Q = I x t Energy = Charge x Voltage –E = Q x V Energy = Current x Voltage x Time –E = I x V x t Energy = Power x Time –E = P x t Cost of Electricity = Power x Time x Cost of 1 kWh

Which line of best fit would you use to show this pattern? Best curve.  What would an estimate for 7V be? Why is this only an estimate?

Capacity (batteries) = Current x Time –Capacity = I x t Payback Time = Installation Cost Annual Saving Efficiency = Useful Output x 100 Total Input

Voltage, Current, and Energy To transfer a lot of electrical energy you either need a high voltage or a high current –P = I x V The problem with high current is the loss (as heat) due to the resistance of the cables –P = I 2 x R It is much cheaper to increase the voltage This keeps current low, meaning less wasted energy (higher efficiency)

Practical Skills Variables –Independent and Dependent –How are they set up in a table? on a graph? Emphasis on ‘accurate and reliable results’ –Concept of fair testing –Repeating the experiment

Tables and Graphs –How are anomalies identified? –How can the problem of anomalies be eradicated? Always draw a scatter graph unless told otherwise –Lines / Curves of Best Fit always included Label axes / Column headings with correct units

Paying up Work sheet P1a (1 and 2)

What are the benefits of using energy more efficiently?