Video Transcript
The picture shows the circuit
symbol for a cell. Which line represents the negative
terminal of the cell?
Here, we have a diagram of a cell
from an electric circuit. And we want to know which line, the
shorter or longer one, represents the negative terminal of the cell.
Let’s recall that conventional
electric current always points away from the longer line and toward the shorter line
of the cell. We can show this on the
diagram. Also, we should remember that
conventional current was defined under the assumption that current is the flow of
positive charge carriers. Because of this, conventional
electric current points away from the positive terminal and toward the negative
terminal.
Since conventional current points
away from the longer line, we know that the longer line represents the positive
terminal. And so, the shorter line represents
the negative terminal. Therefore, the shorter line
represents the negative terminal of the cell.
As a side note, we reach the same
conclusion if we think about the direction of electron flow rather than conventional
current. Recall that electrons flow in the
opposite direction of conventional current. So we can show electron movement in
pink, pointing in the opposite direction of the conventional current that we showed
in orange. Because electrons are negatively
charged, they move away from the negative terminal, which, as we know, is
represented by the shorter line.
