The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity and Errors

1.4

The Use of Measuring Instruments, Accuracy, Consistency, Sensitivity and Errors

Measuring Length

Definition

Length is the distance between two points.

Can be measured in millimetres (mm), centimetres (cm) or kilometres (km).
Can be measured using Vernier calipers where it can measure the thickness of outer diameter, inner diameter and depth of an object.
Vernier calipers is more accurate compared to a ruler

Systematic error - caused by using measuring instruments that are no accurate
Example: Zero error can be determined when the jaws of the vernier calipers are closed.

To obtain the actual reading, zero error has to be taken into consideration.

Actual reading = Reading of vernier calipers - zero error

Measuring Mass

Definition

Mass is the quantity of matter in it

Mass can be measured using digital electronic balance accurately and precisely

Measuring Time

Definition

Length is the distance between two points.

Time can be measured using stopwatch accurately to 0.01 seecond

Measuring Temperature

Definition

Temperature is the degree of heat of an object

A digital thermometer can give accurate reading of temperature up to \(0.1^\circ\text{C}\)

Measuring Electric Current

Ammeter is used to measure electric current in a circuit
A digital ammeter gives more accurate and precise readings with accuracy up to 0.01A.

Measuring Volume of Water

A measuring cylinder can measure the volume of water
Parallex error occurs when the reader's eyes are not peperndicular to the reading scale

How to minimise systematic errors and random errors:

Systematic Errors

Zero error
Inaccurate measuring instrument

Ways to ovecome

Conduct experiments with caution
Repeat experiment using different measuring instruments

Random Errors

Parallax error
Carelessness of observer when taking the reading
Wrong technique

Ways to ovecome

Take a few readings of measurement and take the average reading
To reduce impact of parallax error, observer eyes should be perpendicular to the scale reading