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Measuring resistance

I have a quick question: when we measure the resistance in a circuit, why do we have to use a variable resistor? Why can't we just simply change the voltage on our power supply?


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Original post by kingaaran
I have a quick question: when we measure the resistance in a circuit, why do we have to use a variable resistor? Why can't we just simply change the voltage on our power supply?


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Because resistance is the variable to be explored, the experiment needs to ensure all other variables stay constant.

Using a variable resistor and keeping the supply constant, will put a control limit on the maximum current that can flow through the resistance..

i.e. the power dissipated in the resistance is limited such that it does not overheat, destroy the resistor and most importantly, does not introduce a thermal variable into the experiment.
(edited 9 years ago)
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crashMATHS
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Original post by uberteknik
Because resistance is the variable to be explored, the experiment needs to ensure all other variables stay constant.

Using a variable resistor and keeping the supply constant, will put a control limit on the maximum current that can flow through the resistance..

i.e. the power dissipated in the resistance is limited such that it does not overheat, destroy the resistor and most importantly, does not introduce a thermal variable into the experiment.


Oh okay then, that seems to make much more sense now


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