Question

Why as the temperature increases does the electrical conductivity decrease in metals but increase in electrolytes? Why do two circular current loops of the same size and with the same current direction attract each other when one is placed on top of the other but repel each other when they are placed side by side on the same plane? What happens in these two situations if the directions of current are opposite in the two loops? What are the similarities and differences for the microscopic basis of paramagnetism versus the microscopic basis for orientational polarization in dielectric materials? What are the similarities and differences for the microscopic basis of diamagnetism with the microscopic basis for electronic polarization in dielectric materials?

Answer 1

a) In metal, electron is responsible as the charge carrier. A systematic flow of electrons in one direction will cause the metal to conduct electricity efficiently. An increase in temperature will cause the electrons to get excited and this causes them to move in a not so orderly manner. Hence, they become less efficient as the charge carrier and conductivity decreases.

In electrolyte, it is the ions (both positive and negative) that is responsible as the charge carrier. An increase in temperature will increase the energy of the ions and they will move faster. Hence its efficiency as charge carrier increases and this will cause the conductivity to increase.

b)
Consider a circular loop of wire lying in the plane of a table. Let the current pass clockwise. The direction of the magnetic field is perpendicularly downward on the plane of the table inside the loop. Hence when two ciruclar loop are placed one upon the other, they repel each other because magnetic field is perpendicularly downward.