# __Fundamental Quantity__ –__ Length__

__Fundamental Quantity__–

__Length__

Length is a measure of distance. In the International System of Quantities, length is a quantity with dimension distance. In most systems of measurement a base unit (Fundamental Unit) for length is chosen, from which all other units are derived.

**In the
International System of Units (SI) system the base unit for length is the
metre.**

Q. How 1 metre is defined?

Ans: Since 1983,
the metre has been internationally defined as **the length of the path
travelled by light in vacuum during a time interval of ****1/299 792 458 of
a second** by using a light source of
known and stable wavelength.

**Length**
is the measure of one spatial dimension, whereas **area** is a measure of two dimensions (length squared) and **volume **is a measure of three dimensions
(length cubed).

Various terms for the length
of a fixed object are used, and these include **height, width or breadth and depth.**

__ Measuring Devices__:-

Vernier CaliperTo know more about vernier callipers |

Ruler |

Screw Gauge |

__Learning Beyond__:

__About Light
Year__

Often we get confused with the term ‘Light Year’

We often relate Year with time like One Year = 365
days= 8,764 hrs. = 5, 25,840 minutes

So thought comes in our mind that Light Year is use as
a unit of time.

But that is not the case.

Light Year is a unit to measure very large celestial
distance

1 Light Year = Equivalent to distance that light
travels in one year with a **speed **of
approx. **30, 00, 00,000 m/s**

And that nearly equals **1 Light year=****9.4607 × 10 ^{12} km**, and it’s enormous!

Because of
its enormous value, its use to define the distances of astronomical bodies.

Some
Examples:

__The Nearest Star to our Solar System__:
Proxima Centauri

__Distance__: 4.26 Light Year

__Farthest Object till date__: Galaxy
GN-z11

__Distance__: 13.4 Billion Light Year

GN-z11
superimposed image

__ Here's some PDF for better understanding__:-

Mind Map for length:-Rainbow mind map of length- Conversion:- Learn To Convert

__ ____Here's some Google Forms to fill up__:-

Quiz:- Quizzo- Students Corner:- Students work

**Students Work**:-

Abhilasha Jha, Jamshedpur |

__Sanvi Mishra, Amritsar__

__Arpita Mishra, Jamshedpur__Arpita Mishra, Jamshedpur |

AUTHOR

RITU

** LINK TO OUR OLD BLOGS**:-

1)
Physical Quantities ✅ on 16^{th}
Sept’ 2021

2)
Fundamental Quantity - Mass ✅ on 18^{th} Sept’ 2021

3) Physical Quantity – Weight ✅ on 22^{nd} Sept’2021

Brilliantly Presented!

ReplyDeleteBrilliant explanation.

ReplyDeleteNicely explain . useful information

ReplyDeleteCommendable Work....keep doing

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