Video Transcript
The graph below shows the output
potential difference of a generator over time. What is the period of the output
potential difference?
To answer this question, we need to
use the graph given to work out the period of the output potential difference of a
generator. We can see that this graph has the
output potential difference in volts plotted on the 𝑦-axis and the time in
milliseconds plotted on the 𝑥-axis. The period is the time taken for
one complete oscillation to occur. We could look at any oscillation on
the graph to work this out, but it’s probably easiest to look at this first one
here.
Notice that we’re including this
starting point here, the maximum value, the minimum value, and these two zero
crossings here in one single oscillation. It’s important that we include the
whole oscillation in our working; otherwise, we won’t find the right value for the
period.
The time taken for this oscillation
to occur is simply equal to the time difference between this point here on the time
axis, which corresponds to the start of the oscillation, and this point here, which
corresponds to the end of the oscillation. So all we really need to do is read
these values from the graph. The scale marked on the horizontal
axis tells us that five of these vertical gridlines corresponds to 500
milliseconds. So we know that each grid line must
represent 100 milliseconds.
The oscillation begins at a time of
zero milliseconds and ends at the second gridline, which corresponds to a time of
200 milliseconds. The period of the oscillation is
equal to the time difference between these two times. So the period is equal to 200
milliseconds minus zero milliseconds. This is simply equal to 200
milliseconds.
So, the answer to this question is
that the period of the output potential difference is equal to 200 milliseconds.
