Question 8: Why rise in the temperature of a conductor is accompanied by a rise in the resistance?
Resistance is the opposition offered by the conductor to the flow of electrons. This resistance comes due to the collision of conduction electrons with the lattice atoms of the conductor and the bound electrons. Clearly, it depends upon the space among the lattice atoms on which the free electrons move. Now when the conductor heats up through any means, the atoms in the conductor gains energy and vibrate more vigorously with greater amplitudes. This narrows the space for the free electrons to move and collide with the atoms more frequently as compared to the colder state. Therefore, the resistance of the conductor increases. It has been found that
R1 and R2 being the resistances of the conductor in colder and hotter state, respectively, ∆t is the change in temperature and α is called the temperature coefficient of the resistor.