## 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.

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