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Question
Which of the following quantities does not change when a resistor connected to a battery is heated due to the current?
Options
Drift speed
Resistivity
Resistance
Number of free electrons
Solution
Number of free electrons
As the resistor connected to the battery is heated, the thermal energy of the electrons increases. Thus, the relaxation time of the electrons will decrease and so will the drift velocity. Resistivity is inversely proportional to the relaxation time; thus, resistivity will increase with decrease in relaxation time. Therefore, resistance will also change. The number of electrons in a resistor will remain same.
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