Measuring instruments are used to measure different physical quantities, such as length and volume. Different instruments are used according to the quantity being measured.

1. Metre Rule

A metre rule is a graduated stick that is one metre long. It is used to measure the length of an object or the distance between two points.

A metre rule is divided into 100 equal centimetres, and each centimetre is further divided into 10 millimetres. Therefore, it can measure lengths accurately to the nearest millimetre.

Important points:

• Place the metre rule along the length being measured.

• Keep your eye vertically above the reading point to avoid an incorrect reading.

• It is better to start measuring from the 1 cm mark if the zero edge of the rule is worn. Subtract 1 cm from the final reading.

2. Measuring Cylinder

A measuring cylinder is a laboratory instrument used to measure the volume of liquids. It has graduated markings that help determine the volume of a liquid.

The surface of a liquid in a measuring cylinder is usually curved. This curved surface is called the meniscus.

• Most liquids form a meniscus that curves downwards.

• Mercury forms a meniscus that curves upwards.

• To obtain the correct reading, position your eye at the same level as the meniscus.

3. Measuring Flask

A measuring flask is a laboratory instrument used to measure a specific volume of liquid. It is useful when preparing solutions that require a measured volume.

The markings on the flask help determine the required volume of liquid.

4. Pipette

A pipette is a laboratory instrument commonly used in chemistry and biology laboratories to measure and transfer a small volume of liquid.

Pipettes are available in different shapes and sizes and may be made of glass or plastic. They are graduated to a specific mark, and commonly available sizes include 10 mL to 25 mL.

Summary of Measuring Instruments