Measuring Instruments

In a laboratory, different instruments are used for different measurements. Do you know what these instruments are? In this lesson, we will be learning about these different instruments and their units. We will be measuring:

1. Time

2. Mass

3. Volume

Time is the variable which has to be kept same for a fair reaction. Do you know which instrument is used to measure accurate time? There are many instruments but digital stopwatch gives the most accurate results. It measures time in 0.01 seconds. Standard unit of time is seconds. Another instrument for measuring time is an analogue watch. It gives the result in 0.1 seconds. To measure time for a hundred meter race, one has to use a digital stopwatch. Standard units (S.I.) are the globally used units and are a common standard for measurement for all scientists.

Mass is measured using different balances. It is the amount of matter in a substance. Its standard unit is kilograms (kg). Some other units are grams, used for very small masses, and tones, used to measure the mass of heavy objects for example vehicles. Beam balance and electronic balance measures masses. Electronic balance is more accurate as it gives reading in 0.01 grams while beam balance gives in 1g.

• 1kg = 1000g

• 1 tone = 1000 kg

Volume needs to be measured accurately. The S.I. unit for volume is cubic centimeters. Other units are meter cube and cubic decimeter.

• 1 meter cube is equal to 1000 decimeter cube

• 1 decimeter cube is equal to 1000 centimeter cube.

Apparatus for measuring volume is measuring cylinder, conical flask, beaker, pipette and burette. Apparatus depends on the volumes we are measuring. The most accurate is a burette. Precision for a burette is 0.05 cubic centimeters. Precision is the smallest measurement an apparatus can measure. For measuring cylinder its precision is 0.5 cm³ and for pipette its precision is 0.1 cm³. While other apparatus have unfixed scales. For measuring volume of a liquid, one has to take care of its meniscus: upper and lower. Meniscus is the curve formation on a liquid. When and upper meniscus forms we read the readings from above and when a lower meniscus forms we read the readings from below.

Gases: For measuring the volume of a gas, we use a gas syringe or a gas jar. Precision of both is 0.2 cm³.