Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds

Further note on component characteristics

Conductance and resistance 
In some circumstances it is useful to consider the conductance of a component rather than its resistance. An increase in conductance suggests an increase in charge carriers – which is often the case when the ‘resistance’ is said to decrease. Using both terms can help students get a feel for the microscopic changes that are altering measurable quantities. 
Why use a variable resistor? 
Students are occasionally confused when the independent variable does not change in a regular manner. Including the variable resistor allows this to happen, but confident students can simply leave it out and use the power supply to produce their own figures for the voltage values. 
Voltage or potential difference? 
Voltage is an everyday term which may suit students at an introductory level, but they should later be encouraged to use the correct, descriptive term ‘potential difference’. 
Using a potential divider 
More able or experienced students can be encouraged to construct a potential divider circuit as shown in these experiments. This will allow them to gain a full range of readings.


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