Other Sources of Error(Error in Weighing)
المؤلف:
D. A. Skoog, F. J.Holler, D M. West, and S. R. Crouch
المصدر:
Fundamentals of Analytical Chemistry
الجزء والصفحة:
9th. p 25
16-4-2017
1908
Other Sources of Error(Error in Weighing)
A porcelain or glass object will occasionally acquire a static charge sufficient to cause a balance to perform erratically. This problem is particularly serious when the relative humidity is low. Spontaneous discharge frequently occurs after a short period. A lowlevel source of radioactivity (such as a Static-Master® photographer’s brush containing a miniscule amount of polonium) in the balance case will ionize enough ions to neutralize the charge. Alternatively, the object can be wiped with a faintly damp chamois.
The optical scale of a single-pan mechanical balance should be checked regularly for accuracy, particularly under loading conditions that require the full-scale range. A standard 100-mg mass is used for this check.
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