When a current flows through a junction or a contact between two metals of different conductivities a charge is accumulated in the vicinity of contact. The charge accumulated, I've read, is directly proportional to the current. In case current flows from a metal of large conductivity to a metal of small conductivity, charge accumulation is of positive type. Why so? And if there is such an accumulation of charge, won't a potential barrier be set up, that will eventually stop current flow?

  • $\begingroup$ considering a gaussian surface may be helpful... $\endgroup$ Commented Dec 28, 2020 at 17:02

1 Answer 1


The two metals will have differing dielectric constants and hence different electric fields, so when considering a gaussian surface, the net flux will NOT be 0. Hence we can assume accumulation of charges. The current will not stop as this accumulation of charges will be overpowered by the cell voltage.


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