Weighing Scale - Sources of Error

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