Laboratory 1. Measurement of Length
Comments to the Instructor
For this laboratory in particular it should be strongly emphasized that students read
... [Show More] very carefully the General Laboratory Instructions section before reading the laboratory.
Throughout this laboratory manual repeated measurements are called for whenever it is feasible. This demonstrates to students the statistical nature of the measurement process. The main goal of this first laboratory is to introduce the idea that the mean of a set of measurements is the most probable value of the measured quantity, and the standard error is a measure of the precision of the results. In addition the concept of propagation of errors is presented. A distinction is made between the approximation to error propagation represented by the concept of significant figures and the more exact approach using the standard error of the measured quantity when it is known.
It is strongly recommended that students be encouraged to purchase a calculator which is pre‐programmed to calculate the mean and standard deviation. For use in later laboratories the calculator should also have pre‐programmed routines to perform linear least squares fits to two parameter data.
For this particular laboratory it would be instructive to ask the students to perform the mean and standard deviation calculations both using the pre‐programmed routines and directly from the equations given. This will emphasize for the students exactly what operation is being performed by the pre‐programmed calculator routine.
The point is for students to observe the statistical variation of random errors. If a mistake is made in reading the meter stick for one or more of the repeated measurements, the resulting error in a single measurement may be so large and non‐random that the whole process becomes meaningless. Caution students to be extremely careful and encourage them to check each other in these measurements in order to avoid such personal errors.
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