## Sunday, April 12, 2009

### [Physics Form 4] Measurements Matter

When selecting a device to measure a quantity, factors like the
• type of quantity to be measured
• estimated size of the quantity
• sensitivity of the device
• accuracy of the device
need to be taken into account because sensitivity, precision and accuracy are the three important properties of a measurement.

Sensitivity is the ability of a measuring device to detect small changes in the physical quantity measured.

Eg: A miliammeter is more sensitive than an ammeter. This is because a ammeter is able to measure a smaller magnitude of electric current in the order of mA, in contrast to an ammeter, which measures a larger current in the order of A.

Precision is the ability of a measuring device to give consistent reading after several repeated measurements. The smaller the relative deviation of a set of readings, the higher is the precision level of the measurements.

Accuracy is the ability of a measuring device to provide readings that are exactly the same as, or close to, the actual value of measurement. the closer a measurement is to its actual value, the higher is its accuracy level.

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