In a mosfet transistor, we call the source the source because it is the source of charge carriers (electrons for n-channel and holes for p-channel) and the drain because it is the drain of the charge carriers. Why is emitter called emitter and the collector called collector in BJT? is it for the same reason? Because in npn the charge carriers are the electrons and in pnp the charge carrier are the holes so emitter would be the emitter of the charge carriers and collector would be the collector of the charge carriers?

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    \$\begingroup\$ The emitter emits charge carriers into the collector that ermm collects them. \$\endgroup\$
    – Andy aka
    Jun 4, 2017 at 19:56
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    \$\begingroup\$ It probably has something to do with electron flow versus conventional current. \$\endgroup\$ Jun 4, 2017 at 19:56
  • \$\begingroup\$ The forward-biased base-emitter junction is flooded with carriers, because the base-current needs to be recombined and cancelled. Fortunately the base is so thin and runs a long distance parallel to the collector region that most of the emitter-provided carriers are swept by the high collector voltage into the collector region, providing an excellent multiple of the base current. \$\endgroup\$ Jun 4, 2017 at 23:58

1 Answer 1


Your hunch is exactly right: the emitter emits charge carriers into the collector, which collects them.


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