Revision as of 03:54, 13 April 2008

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Outcomes

• Pupils can
• Use of P = IV, higher currents leads to hotter wires
• Ammeter in series, voltmeter in parallel

Specification References

2.6 recall and use the relationship, power = current x voltage, P=IV and apply the relationship to the selection of appropriate fuses

Starter

Intro to practical

Main Body of Lesson

• Use of different fuse wires to discover the heating effect of a wire depends on current, thin wires heat up more for same current

Plenary

• Thin wires heat up more – use of this idea to break a circuit
• Use – fuses
• Dangers of fire when using the wrong flex in low current appliances

Homework

Worksheet: Practice using P=IV and choosing fuse values

Additional Information

Resources Required

• Various fuse wires, heat proof mats, high current variable dc supplies, ammeters, voltmeters, 2.5V bulbs.
• P=IV and fuse value practice sheet

Textbook References

Website References

Skills Addressed

Practical skills – building circuits

Safety/Hazards

Burns – students must not touch wires

Notes