3-ELE-08
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Contents
Outcomes
- Pupils can plan a Current-Voltage investigation
- Pupils can select the correct equipment and use an appropriate circuit to take valid measurements
Specification References
2.14 recall and use the relationship between voltage, current and resistance: voltage = current × resistance
Starter
- Pupils to design a circuit to design a circuit from:
a power supply, a variable resistor, an ammeter, a voltmeter, some sample wire
- Pupils to consider how to make the experiment as accurate as possible
Main Body of Lesson
Planning:
- Identify what factors could affect resistance of a wire (length, csa, material, temperature)
- Discuss how to make the experiment fair (control variables) and accurate (several values of V and I)
Observation:
- Pupils to investigate how length affects resistance (use the thickest wire)
- Pupils to investigate how csa affects resistance
- Pupils to record their results on preprtinted table to save time
Plenary
- Pupils to summarise thier findings in two simple tables (length and average resistance, area and average resistance) and discuss their findings in general as a group. This will need to be finsihed prior to the following lesson for data analysis
Homework
- Finish any unfinished tables
- Research the concept of resistivity and find the resistivities of the following:
iron, copper, constantan, nichrome, silver, gold,
- Beware the following page: resistivity on wikipedia
Additional Information
Resources Required
- Class set of power supplies, simple ammeters, simple voltmeters, variable resistors (small value), wire boards, croc clips
Textbook References
Website References
Skills Addressed
Planning and carrying out a practical investigation
Safety/Hazards
- Thin wires can get quite hot - do not let pupils use currents over half an Amp.
