IMAGE. The meter on a Spectronic 20™ viewed such that parallax has been eliminated.
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Step 1: Determine the scale increment:
To find the scale increment, subtract the values of any two
adjacent labeled graduations and divide by the number of intervals
between them.
What is the scale increment on the Spectronic 20™? Answer
On the Spectronic 20™, first subtract 60%T -50%T = 10%T. Next, count that ten intervals are between the labeled graduations. Therefore, the scale increment is 10%T/10 graduation = 1%T/graduation. Step 2: Use the graduations to find all certain digits:
Use the labeled graduations and the scale increment to find the certain digits in the measurement.
What are all of the certain digits on the Spectronic 20™? Answer
The %T is greater than 50%T, since the last labeled graduation below the needle is 50%T. Next, use the scale increment. There are seven graduation marks between the needle and 50%T, and each graduation represents 1%T, so the certain digits of the reading are 57%T. Step 3: Estimate the uncertain digit and obtain a reading:
Estimate the distance that the needle lies between the two graduations as a decimal fraction and multiply by the scale increment.
What is the %T you should record? Answer
The needle is about nine tenths of the way between the two graduation marks. Thus, the uncertain digit is calculated as (0.9 graduation) * (1%T/graduation) = 0.9 %T . And, the volume to be recorded is 57.9 %T. |
