Introduction

In our daily life, we come across many objects and things. We tend to use those things, too. When our mother or father cooks food, we can observe them adding salts, sugar, water, etc. in a calculated way only. Adding more or less of such ingredients ruins the taste of the food. Remember when a teacher asks you to find out how many students are absent in your class, what do you do? Of course, you start counting the number of people and then calculate the number of absentees. We have 24 hours in a day but how can we know that 1 hour has passed? We need to count how many seconds have passed. If 3600 seconds have passed, we say that 1 hour has passed. So, we tend to count or calculate things a lot in our lives. When this calculation is done in a scientific way, we term it as measurement.

Measurement

Measurement is a process of comparing an unkown physical quantity with known physical quantity of the same kind.

• Physical quantities are those quantities that can be measured directly or indirectly. Example: length, volume, time, etc.
• Known physical quantities are those whose values are known to us.
• Unknown physical quantities are those whose values are not known to us. 
• Same kind means if you are going to measure the mass of a bat, you need to use a known standard mass. You cannot compare mass with length to obtain readings.

Imagine you go to vegetable shop to buy some vegetables. You order half a kilo cauliflower. The vendor starts weighing it using a physical balance. The mass of the cauliflower is unknown physical quantity (unkown mass) and the standard measuring weights (0.25 kg, 0.5 kg) that the vendor place on the other plate of a physical balance is known physical quantity (known mass). By comparing the unkown mass of cauliflower with 0.5 kg of known weight, we can then buy half a kilo of cauliflower without being cheated.

Advantages of Measurement

Following are the advantages of measurement:

1. It helps to make scientific calculations easier and faster.
2. It helps to know the value of unknown physical quantity by comparing with known physical quantity of same kind.
3. It helps to find accurate readings.