Measurement - Measurement of Capacity

Capacity refers to the quantity of liquid a container can hold. Imagine a bucket filled to the top with water; the total amount of water it contains is its capacity. It is measured using standard units to ensure accuracy across different containers.

The standard unit of capacity is the Litre ($L$). For smaller quantities, we use the Millilitre ($ml$). To visualize this, think of a large carton of milk as $1 L$ and a small eye-dropper containing about $1 ml$.

There is a fixed relationship between these units: $1 L = 1000 ml$. You can think of a $1$ Litre bottle as being made up of $1000$ tiny $1 ml$ units stacked together.

To convert Litres into Millilitres, we multiply the amount by $1000$. For example, if you have $6 L$ of juice, you have $6 \times 1000 = 6000 ml$. A quick trick is to add three zeros to the right of the number of Litres.

To convert Millilitres into Litres, we divide the amount by $1000$. In a four-digit number of $ml$, the digit at the thousands place represents Litres, and the last three digits represent Millilitres. For instance, $4575 ml$ can be seen as $4 L$ and $575 ml$.

When adding or subtracting capacities, we group the Litres and Millilitres into separate columns. It is important to remember that the $ml$ column should always be treated as a three-digit group. If you add $ml$ and the sum is $1000$ or more, you must carry over $1 L$ to the Litre column.

Measuring tools such as measuring cylinders, jugs, and beakers have markings called graduations on their sides. To read the capacity correctly, you must look at the marking that aligns with the level of the liquid. For liquids like water, the surface slightly curves; always read the level at the bottom of this curve (meniscus) while keeping your eyes level with the liquid.