Sources of Error
Some of the sources of error in weighing are:
- Buoyancy, Objects in air develops buoyancy force that is directly proportional to the volume of air displaced. The difference in density of air due to barometric pressure and temperature creates errors.
- Error in mass of reference weight
- Air gusts, even small ones, which push the scale up or down
- Friction in the moving components that cause the scale to reach equilibrium at a different configuration than a frictionless equilibrium should occur.
- Settling airborne dust contributing to the weight
- Mis-calibration over time, due to drift in the circuit's accuracy, or temperature change
- Mis-aligned mechanical components due to thermal expansion/contraction of components
- Magnetic fields acting on ferrous components
- Forces from electrostatic fields, for example, from feet shuffled on carpets on a dry day
- Chemical reactivity between air and the substance being weighed (or the balance itself, in the form of corrosion)
- Condensation of atmospheric water on cold items
- Evaporation of water from wet items
- Convection of air from hot or cold items
- Gravitational differences for a scale which measures force, but not for a balance.
- Vibration and seismic disturbances
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