Video Transcript
The picture below shows the top
parts of several graduated cylinders. Which of the following graduated
cylinders can give the most accurate measurement?
Accuracy describes how close a
measurement is to a true or accepted value. So the most accurate measurement
will be the measurement that is the closest to the true value. To help us determine which of the
graduated cylinders can give the most accurate measurement, let’s assume that each
of the graduated cylinders is the same size. This means that the only difference
between the graduated cylinders is the number of markings or graduations they
have.
Three of the markings are in the
same location on all four graduated cylinders. Let’s assign these markings the
values 12, 16, and 20 milliliters to make the graduated cylinders easier to
compare. To each of the graduated cylinders
we’ll add exactly 17.3 milliliters of water. This will represent the true
value. When water is added to a graduated
cylinder, the surface of the water tends to curve downwards. This is due to the surface tension
of the water and the adhesive forces between the water molecules and the glass. The curvature of a liquid surface
is called the meniscus. For simplicity, the surface of the
water in each of these graduated cylinders is shown as a straight line rather than
as a curve. Let’s see what the markings
provided on each graduated cylinder can tell us about the volume of water
contained.
Looking at graduated cylinder (A),
we can see that the volume of water is between 16 and 20 milliliters. We can also see on graduated
cylinder (B) that the volume is between 16 and 20 milliliters. But because there are more
markings, we can narrow down this range even further. The graduations on this graduated
cylinder increase by 0.5 milliliters. So we can see that the volume of
water is between 17 and 17 and a half milliliters. The graduations on graduated
cylinder (C) increase by two milliliters. So we know the volume of water is
between 16 and 18 milliliters. The graduations on graduated
cylinder (D) each increase by one milliliter. So we know the volume of water is
between 17 and 18 milliliters.
We can see that graduated cylinder
(B) has the smallest error margin. This means that using graduated
cylinder (B) will produce measurements that are the closest to the true value. Therefore, the graduated cylinder
that can give the most accurate measurement is the graduated cylinder that has the
most graduations, in this case graduated cylinder (B).
