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# Measurement – CBSE NCERT Science Lesson

#### Measurement – CBSE NCERT Science Lesson

It is the comparison of an unknown quantity with a known fixed quantity called “UNIT”.

Things one should know in order to measure any particular quantity.

The unit of measurement

The number of units that particular quantity measures

#### Measurements in Ancient Times

HANDSPAN

CUBIT

FOOTSTEP

A YARD

ARM LENGTH

INTERNATIONAL SYSTEM OF UNITS

Different standard units of measurement were created at different places. For the sake of uniformity, scientists all over the world have accepted a set of standard units of measurement……

This standard system of unit is known as the INTERNATIONAL SYSTEM Of UNITS..i.e., SI units

FUNDAMENTAL UNITS

DERIVED UNITS

MEASUREMENT OF LENGTH

LENGTH IS MEASURED AS A DISTANCE BETWEEN TWO POINTS OR OBJECTS.

THE STANDARD UNIT OF MEASUREMENT OF LENGTH IS A ‘METRE’ WHICH IS WRITTEN AS ‘m’.

THE MEASURED VALUE CONSISTS OF TWO PARTS.

E.g: If the length of a desk is 2m, it means that a meter length is repeated 3 times.

INSTRUMENTS USED FOR MEASURING LENGTH

MEASURING TAPE

METER RULER

METER ROD

METER SCALE

The type of instrument depends on the type of work and the accuracy that is needed

PARALLEX ERROR

An error caused due to the wrong position of eye while taking the readings.

Measuring the length of a curved line

Put a knot near one end of a thread.

Place the knot at the beginning of the line at A and press it with your thumb.

Place a portion of the thread along the curved line and press it with your forefinger.

Keeping your finger pressed move the thread along some portion of the line.

Repeat the steps 3 and 4 to trace the entire length of the curved line using the thread.

When the thread reaches the end, put a mark on it.

Stretch out the thread on a scale and measure its length with the help of a measuring scale.

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