Understanding Measurement

A micro balance is used to measure minute masses. It is sensitive but not very accurate.


Slide callipers are usually used to measure the internal or external diameter of an object.


A micrometer screw gauge is used to measure the diameter of a wire of the thickness of a thin object.

All measurement must consider this:

Accuracy: Ability of the instrument to measure the true value or close to the true value. The smaller the percentage error, the more accurate the instrument is.

Sensitivity of an instrument is the ability of the instrument to detect any small change in a measurement.

Consistency: ability of the instrument to produce consistent measurement.(the values are near to each other). The lower the relative deviation, the more consistent the measurement is.

How to increase accuracy?
- repeat the measurements and get the mean value.
- correcting for zero error.
- avoiding parallax error.
- use magnifying glass to aid in reading.

The sensitivity of a mercury thermometer can be increased by;
-having a bulb of thinner wall.
-having a capillary tube of smaller diameter or bore.