Notes
When you are reading a
graduated cylinder, it is critical
that you take the time to look
closely at the markings and
understand the spacing. Not all
graduated cylinders are the
same, so you can’t assume a
certain marking pattern. In the
picture above each milliliter is
marked (19, 20, 21, and 22).
In addition, there are nine lines
in-between each milliliter value
so each of these lines
represents one-tenth of a
milliliter. When reading the
graduated cylinder in the
picture above, I see the bottom
of the meniscus is in between
the 1st and 2nd line after the 20
mL mark. Notice that the
bottom of the meniscus is
likely to not fall exactly on a
marking, which allows us to
interpolate the value to get the
correct value along with an
estimate of the uncertainty.
My thought process for reading
the cylinder in figure 3.6 is first
to note that the value is
somewhere between 20 and 21 mL, then I go a step further and see it is
between 20.1 and 20.2 mL, and then finally I make my determination of the
recorded value by estimating the last digit. It looks as if it is closer to 20.2 mL
than 20.1 mL, so I would read it as 20.18 mL. Someone else might come along
and have a slightly different estimation of the last digit, maybe they think that it
is 20.16 mL or 20.19 mL. This slight disagreement is fine and gives an
approximation of the uncertainty of the measurement. I would record this value
with four significant digits since my last recorded digit should be the one that has
uncertainty.
26
Figure 3.6: "Buret" by photobunny is licensed under CC BY-NC-