out window. After the "remove weight" appears, turn each of the controls back one
step. If the "remove weight" does not appear even when the knob is in its highest
position, leave it in that position; do not turn back one step.
w. On the model 10N, balance if the digitizer drum is between numbers during
the weighing process, move the number that shows the most into full view. On the
model 21 in Figure 9 or similar balances, you have a micrometer instead of a
digitizer. When the scale stops, turn the micrometer knob slowly until the scale
line just below the reference gap is centered in the gap.
There is a slight
difference in the interpretation of the two scale readings.
x. Read the model 10N scale in Figure 5A, from left to right as indicated.
You should realize that the balance optical scale is extended beyond 100 divisions
for easier weighings near the scale ends. The first "1" of the divisions 100-120
has to be carried mathematically into the digits at the left. The results of the
weighing by the model 21 balance in Figure 9 are read from the left to the right--
digits in the windows first, optical scale second, and micrometer scale last. Tens
of milligrams (45 in the example of Figure 9) are read on the optical scale. Read
milligrams and tenths of milligrams are the micrometer scale (6.7 in the example).
The fact that each line on the optical scale is equal to 10 milligrams (not 1 mg)
could cause some confusion.
For this reason, you should record each digit as a
separate number without regard to the significance of each digit. To complete your
study of the material in this lesson, answer the review exercises prepared for this