### Video Transcript

Nine identical cells are connected
in parallel and are all aligned in the same direction. The total emf provided by the cells
is 18 volts. What is the emf provided by one
cell?

First, let’s make a sketch of the
information given and what the question asks.

The question asks about nine
identical cells connected in parallel. In our diagram, we will show that
the positive terminals of all the cells are all connected together on the same
side. And all of the negative terminals
are connected together as the cells are all aligned in the same direction. The total electromotive force
provided by the cells is 18 volts.

The question asks us for the emf
provided by any one cell. So we have to think about what
happens when cells are connected in parallel. We know the cells must all have the
same emf values because the question states that the cells are identical. When identical cells are connected
in parallel, the total emf supplied to the circuit is the same as the emf of any of
the cells, and the total current produced is the same too. This is because the potential
difference between points one and two is the same for all paths that we choose in
the circuit. It doesn’t matter which cell we
pass through to go from point one to point two.

The total emf supplied to the
circuit is 18 volts. So we know that all the cells,
which are connected in parallel, all supply the same emf as the total emf. Any one of the cells supplies an
emf of 18 volts.