
	Topic
1	Map & Internet of Physics
2	100 Questions
3	Ved Vigyan Alok
4	Vaidic & Modern Physics Research Centre

Map & Internet of Physics[edit]

वैदिक सृष्टि–विज्ञान | Vaidic Physics[edit]

Modern Physics[edit]

SI Based Units[edit]

SI defining constants
Symbol	Defining constant	Exact value
Δν_Cs	hyperfine transition frequency of Cs	9192631770 Hz
c	speed of light	299792458 m/s
h	Planck constant	6.62607015×10⁻³⁴ J⋅s
e	elementary charge	1.602176634×10⁻¹⁹ C
k	Boltzmann constant	1.380649×10⁻²³ J/K
N_A	Avogadro constant	6.02214076×10²³ mol⁻¹
K_cd	luminous efficacy of 540 THz radiation	683 lm/W

SI base units
Name	Symbol	Measure	About	Post-2019 formal definition^[1]	Historical origin / justification	Dimension symbol
second	s	time	The second is the basic unit of measurement for time. Because we now have a way to observe time in its smallest unit or form, this was helpful especially in sports and science. Before, 1 second was first used to describe the time spend in the earth’s rotation. Today 1 second is 1/60 of a minute based on the numerical conversion.	"The second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency, ∆ν_Cs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9192631770 when expressed in the unit Hz, which is equal to s⁻¹."^[1]	The day is divided into 24 hours, each hour divided into 60 minutes, each minute divided into 60 seconds. A second is 1 / (24 × 60 × 60) of the day. Historically, a day was defined as the mean solar day; i.e., the average time between two successive occurrences of local apparent solar noon.	T
metre	m	length	The meter is used to calculate distance or length. When scientists first thought of the meter, it was described as one ten-millionth of the distance between the equator and the North Pole. Comparing with other metric systems, 1 yard is exactly 0.9144 of a meter.	"The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299792458 when expressed in the unit m s⁻¹, where the second is defined in terms of ∆ν_Cs."^[1]	1 / 10000000 of the distance from the Earth's equator to the North Pole measured on the meridian arc through Paris.	L
kilogram	kg	mass	The kilogram is used to compute for mass, which is the measurement of the quantity of matter in any given object. In science the kilogram is used to measure mass, but for us we use it to measure both mass and weight. One kilogram is actually a thousand grams, and although gram can be considered the chief unit, the kilogram (prefix kilo + gram) is used to define measurement for objects with considerable size. In real life, we use the kilogram more to shorten descriptions of measurement that may be too long for comfort (example, 22,000 grams = 22 kilograms).	"The kilogram, symbol kg, is the SI unit of mass. It is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015×10⁻³⁴ when expressed in the unit J s, which is equal to kg m² s⁻¹, where the metre and the second are defined in terms of c and ∆ν_Cs."^[1]	The mass of one litre of water at the temperature of melting ice. A litre is one thousandth of a cubic metre.	M
ampere	A	electric current	Ampere (abbreviated as A). Amperes or more commonly called amps, is used to measure the electric current. Amps can be used to compute for how much electricity runs in a given object, so all conductors of electricity uses amps to	"The ampere, symbol A, is the SI unit of electric current. It is defined by taking the fixed numerical value of the elementary charge e to be 1.602176634×10⁻¹⁹ when expressed in the unit C, which is equal to A s, where the second is defined in terms of ∆ν_Cs."^[1]	The original "International Ampere" was defined electrochemically as the current required to deposit 1.118 milligrams of silver per second from a solution of silver nitrate.	I
kelvin	K	thermodynamic temperature	The kelvin is used to compute the amount of heat in a certain object. We may be not very familiar with using the kelvin to measure temperature, but it is called the absolute scale because the temperature is only stated in positives (no Kelvin measurement uses the negative sign).	"The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380649×10⁻²³ when expressed in the unit J K⁻¹, which is equal to kg m² s⁻² K⁻¹, where the kilogram, metre and second are defined in terms of h, c and ∆ν_Cs."^[1]	The Celsius scale: the Kelvin scale uses the degree Celsius for its unit increment, but is a thermodynamic scale (0 K is absolute zero).	Θ
mole	mol	amount of substance	To compute for the quantity of substance within an object, SI uses the mole as its basic unit of measurement. Because there are no other available units used to measure the amount of substance within matter, we may also not be aware of using the mole as a unit of measurement, but this is the general term used by scientists	"The mole, symbol mol, is the SI unit of amount of substance. One mole contains exactly 6.022 140 76 × 10²³ elementary entities. This number is the fixed numerical value of the Avogadro constant, N_A, when expressed in the unit mol⁻¹ and is called the Avogadro number. The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles."^[1]	Atomic weight or molecular weight divided by the molar mass constant, 1 g/mol.	N
candela	cd	luminous intensity	The candela is used to measure the brightness or luminous intensity of an object. You can use this to compute for how much light an object emits, or the amount it glows, or simply how bright it is.	"The candela, symbol cd, is the SI unit of luminous intensity in a given direction. It is defined by taking the fixed numerical value of the luminous efficacy of monochromatic radiation of frequency 540×10¹² Hz, K_cd, to be 683 when expressed in the unit lm W⁻¹, which is equal to cd sr W⁻¹, or cd sr kg⁻¹ m⁻² s³, where the kilogram, metre and second are defined in terms of h, c and ∆ν_Cs."^[1]	The candlepower, which is based on the light emitted from a burning candle of standard properties.	J

Dimension:[edit]

The SI standard selects the following dimensions and corresponding symbols: time (T), length (L), mass (M), electric current (I), absolute temperature (Θ), amount of substance (N) and luminous intensity (J).

Mathematically, the dimension of the quantity Q is given by

$\operatorname {dim} Q={\mathsf {T}}^{a}{\mathsf {L}}^{b}{\mathsf {M}}^{c}{\mathsf {I}}^{d}{\mathsf {\Theta }}^{e}{\mathsf {N}}^{f}{\mathsf {J}}^{g}$

where a, b, c, d, e, f, g are the dimensional exponents. Other physical quantities could be defined as the base quantities, as long as they form a linearly independent basis – for instance, one could replace the dimension (I) of electric current of the SI basis with a dimension (Q) of electric charge, since Q = TI.

As examples, the dimension of the physical quantity speed v is

\operatorname {dim} v={\frac {\text{length}}{\text{time}}}={\frac {\mathsf {L}}{\mathsf {T}}}={\mathsf {T}}^{-1}{\mathsf {L}}

and the dimension of the physical quantity force F is

\operatorname {dim} F={\text{mass}}\times {\text{acceleration}}={\text{mass}}\times {\frac {\text{length}}{{\text{time}}^{2}}}={\frac {{\mathsf {L}}{\mathsf {M}}}{{\mathsf {T}}^{2}}}={\mathsf {T}}^{-2}{\mathsf {L}}{\mathsf {M}}

^ ^a ^b ^c ^d ^e ^f ^g ^h "The International System of Units (SI), 9th Edition" (PDF). Bureau International des Poids et Mesures. 2019.

[SI_9th_edition-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h "The International System of Units (SI), 9th Edition" (PDF). Bureau International des Poids et Mesures. 2019.

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