P1a Topic 10 Internal Assessment. Diagram of Electric Motors Coil of Copper WireMagnet Split-Ring...
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Transcript of P1a Topic 10 Internal Assessment. Diagram of Electric Motors Coil of Copper WireMagnet Split-Ring...
P1a Topic 10Internal
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) Fireworkb) Battery-Operated Radioc) Electric Motord) Light Bulbe) Hairdryer
Units of Measurement in Physics
• Voltage ( )
• Current ( )
• Resistance ( )
• Power ( )
• Charge ( )
• Energy ( )
• 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 = I2 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. 10.5 (1 and 2)
What are the benefits of using energy more efficiently?