Episode 107: Preparation for Resistance Topic
This series of activities, from the Institute of Physics, help student to understand electrical resistance. What is resistance, how it can be measured, how it arises and what affects it? During the topic, resistance is related to current, voltage, type of material, temperature and light intensity. The electrical behaviour of different types of material and semiconductors is related to their microscopic structure. The activities also give students practice in setting up electrical circuits and using ammeters and voltmeters.
The learning episodes in this series are:
Episode 108: Resistance
Episode 109: Electrical characteristics
Episode 110: Resistance and temperature
Episode 111: Semiconductor devices
Episode 112: Resistivity
Following completion of this area of study, students should be able to:
1. measure the I -V characteristics of metals, carbon resistors, semiconductor diodes and filament lamps
2. define resistance
3. use an ohm meter
4. state and use Ohm’s law
5. describe and explain the effect of temperature on the resistance of a metal and of a thermistor
6. describe and explain the effect of light on a light dependent resistor
7. investigate the dependence of resistance on length and cross-sectional area using resistive putty and resistive paper
8. make measurements of resistivity
9. perform calculations involving resistivity.
Students should have previously encountered the equation R = V / I, which defines resistance. They should also be familiar with the idea that metals contain free electrons, which is why they conduct well (both electricity and heat).
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