Recording Measurements Using a Scale on an Instrument

Understanding Scales on Instruments

Instruments such as rulers, measuring tapes, thermometers, and weighing scales feature a scale that corresponds to a unit of measure.
A scale is a series of marked intervals on an instrument, used for counting or measuring.
Correctly reading the scale is crucial to obtaining accurate measurements.
The unit of measure will be clearly marked on the instrument - such as centimetres on a ruler or degrees Celsius on a thermometer.
Understand the concept of zero error, which occurs when the measuring instrument’s scale doesn’t start from zero.

Carefully read the measurement value by aligning your object or test condition with the appropriate end of the scale.
Be aware of parallax error, which occurs when the measurement reading changes based on the viewer’s position. To minimise this, keep your eye in line with the mark being read.
When noting down the measurement, include the value and unit. For example, ‘The length of the pencil is 12 cm.’
When measuring length, ensure the object starts from the zero mark on the ruler.
When using a thermometer, ensure the bulb is fully immersed in the substance being measured but not touching the container sides or bottom.

Some instruments, like vernier calipers or micrometres, provide higher-precision measurements and have a secondary scale for more accuracy.
Understand how to correctly read the main and vernier scale on these instruments.
Be aware that these instruments require careful handling to maintain their precision over time.

Applying these principles to real-world situations is essential.
Always ensure your measurements are appropriate and accurate for the task at hand.
Remember to respect and recognise the limit of reading and precision of the instrument you’re using.
Establish whether multiple measurements and an average value might be required.
Reflect on the potential sources of error – from instrument, from user, or from environmental factors.