Measurement Units (मापन के मात्रक/इकाई)- Competitive Physics

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Physics topic – “Measurement Units (मापन के मात्रक/इकाई)“, is important for all competitive exams like SSC CGL, SSC CHSL, RRB NTPC, UPSC and other state civil services exams. In these exams, almost 4-5 questions are coming from Physics. Let’s start the topic – Measurement Units (मापन के मात्रक/इकाई).

Measurement Units

(मापन के मात्रक/इकाई)

Definition of physics: The branch of science concerned with the nature and properties of matter and energy.

Measurement:

In Number: 1) Octal 2) Decimal 3) Hexadecimal
In Unit: The word unit as used in physics binary refers to the standard measure of a quantity.

Units: Unit are mainly two types :-

Basic unit: Total basic unit are 7 ⇒ 6-physics + 1- chemistry
Derived unit: ∞ (infinity)

The SI base units are the standard units of measurement defined by the International System of Units(SI) for the seven base quantities.
I. system starts in 1961 (in jenewa)
In S.I. system dimensional formula is [M L T] where, M for mass, L for length, T for time.

S.I. System:

Sl. No.	Name of the Quantity	SI Unit	SI Unit Symbol
1.	Length (l)	Meter	m
2.	Mass (M)	Kilogram	kg
3.	Time (T)	Second	s
4.	Electric current (I)	Ampere	A
5.	Thermodynamic temperature (Θ)	Kelvin	K
6.	Luminous intensity (J) (light)	candela	cd
7	Amount of substance (N)	Mole	mol

This 7^th unit is Chemistry unit.

Physical Quantities: – These are those quantities which can be measured accurately.

These are mainly two types:

Scalar quantity: The physical quantity with magnitude only, no direction. E.g. Mass, Speed etc.
Vector quantity: A vector is a quantity that has both a magnitude and a direction. For e.g.- force, velocity, acceleration, displacement, and momentum etc.

Some Important Measurement Units of Physics:

1) Light year:–

It is unit of distance through which distance of celestial objects can be measured.

Distance travelled by light in a year is called One-Light-year.
Speed of light= 3 x 10⁸ m/sec
Distance travelled by light in a year = 9.46 x 10¹² KM or 9.46 x 10¹⁵ meters.

2) Parsec: –

It is largest unit of distance by which distance of celestial (astronomical) object can be measured.

It is 3.25 times more than the light year.
1 parsec = 2.49 x 10¹³ k.m. or 2.49 x 10¹⁶ meters.

3) Astronomical unit: –

It is also the unit of distance by which the distance of celestial (astronomical) object can be measured.

It is average distance between Sun and Earth.
1-astronomical unit = 1.5 x 10⁸ Km or 1.5 x 10¹¹ meters .

4) Fermi unit: –

It is the smallest unit of distance through which atomic radius can be measured.

It is Atomic distance between molecules.
1-Fermi = 10^-15 meter

5) Nautical mile: –

This is the unit of distance through which distance in “ocean” as well as “in air” can be measure.

1 nautical mile = 1852 meter

6) Naute: –

It is a unit by which the speed of ship can be measured.

naute = 1852 meter/hours

7) Fathem: –

It is unit by which “Depth of ocean” can be measured.

Fathem = 6 feet

8) Cusec: –

It is unit through which “flow of liquid” can be determine.

- 1 cusec = feet³ /sec

- 1 cusec = 28 litre

9) Poise: –

It is a unit through which viscosity of liquid can be measured.

- Facts: “clouds” floths in the sky due to less viscosity and low density.

10) Pascal: –

It is unit through which “pressure of gas” can be measured.

- 1 pascal = 1 N/m²

11) Diopter: – It is unit through which “power of lens” can be measure.

12) Richter scale: – Unit through which intensity of earth quack can be measured

13) PH- Scale: – Through which “strength of acid and base” can be measured.

14) Curine/Rutherford/Brequell: – These are units through which “Intensity of Radio activity” can be measured.

15) Decibel:- It is unit through which Intensity of the sound can be measured.

16) Aung strung (Aº):- It is unit through which cellular component like membrane etc. can be measured.

- 1 A º= 10^-10 meter

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