घनत्त्व  हिन्दी देवनागरी में पढ़ें।

ghanattv (angrezi:Density) padarth ke ikaee ayatan men nihit dravyaman ko kahate hain. yah samany anubhav hai ki barabar ayatan ke vibhinn padartho ka bhar bhinn-bhinn hota hai. yah bhinnata padarthon ke anuon ya paramanuon ke bhar tatha padarthavishesh men unaki snnikatata par nirbhar hoti hai, kyonki kisi vishesh padarth ke anuon tatha paramanuon ka bhar aur us padarth men unaka rachanakram lagabhag nishchit hota hai. at: padarthavishesh ke nishchit ayatan ka bhar bhi nishchit hi hota hai. ikaee ayatan ke padarth ki matra ko us padarth ka ghanatv kahate hain. yah padarth ki saghanata ka dyotak hai tatha padarth ka vishesh gun hota hai. uparyukt paribhasha ke anusar kisi vastu ka ghanatv nimnalikhit sootr dvara vyakt kiya jata hai:

ghanatv = matra / ayatan

at: sentimitar gram saikind[1] paddhati men ghanatv ki ikaee gram ghan sentimitar hai.

apekshik ghanatv

sadharanataya padartho ke apekshik ghanatv ka gyan adhik upayogi hota hai, yatha kisi padarth ke pind ka kisi drav men doobana ya tairana, drav ki apeksha padarth ke ghanatv ki adhikata ya nyoonata par, nirbhar karata hai. jab ek padarth ke ghanatv ki doosare padarth ke ghanatv se tulana ki jati hai, tab usase jo ank prapt hota hai vah pahale padarth ka apekshik dhanatv kahalata hai. apekshik ghanatv vastut: pahale aur doosare padarthon ke ghanatv ka anupat hota hai. padartho ka apekshik ghanatv kuchh nishchit manak padarthon ke ghanatv ki tulana se vyakt kiya jata hai. yadi a ayatan ke ek padarth ki matra dravyaman1 tatha usi ayatan ke manak padarth ki matra dravyaman0 hai, to uparyukt paribhasha ke anusar padarth ka apekshik ghanatv nimnalikhit sootr dvara vyakt kiya jata hai :

apekshik ghanatv = dravyaman1 / dravyaman0

padarth ka ghanatv ya apekshik ghanatv, vyakt karate samay padarth ki bhautik avasthaon (tap, dab, ityadi) ko bhi vyakt karana avashyak hota hai, kyonki bhautik avastha ke parivartan se ghanatv men kafi parivartan hota hai. ghanatv par tap tatha dab ka adhik prabhav padata hai. yah parivartan padarth ke ayatan parivartan ke karan hota hai.

thos tatha drav padartho ke ayatan, tadanuroop unake ghanatv, par samany dab parivartanon ka prabhav itana sookshm hota hai ki samanyataya vah upekshaniy hota hai. doosari or samany tap parivartanon ka prabhav upekshaniy nahin hota hai. at: thos tatha drav padarthon ke ghanatv ke sath-sath unaka tap vyakt karana hi paryapt hota hai. dab ko vyakt nahin kiya jata. samanyat: thos tatha drav padarthon ka apekshik ghanatv 4° sentigred par pani ke ghanatv ki tulana se vyakt kiya jata hai. yah avashyak nahin ki padarth tatha pani ka tap ek hi ho. apekshik ghanatv ko nimnankit prakar se likhate hain:

(1° /0°)

yahan (1°) padarth tatha (0°) pani ka tap hai, tatha () padarth k apekshik ghanatv hai. yah smaran rakhana chahie ki 4° sentigred par pani k ghanatv ek gram/prati ghan sentimitar hota hai. at: 4° sentigred par pani ke ghanatv ki tulana se kisi padarth ka apekshik ghanatv hi usaka ghanatv bhi hota hai. suvidhanusar pani ke sthan par any padarth bhi manak ke roop men prayukt hote hain.

gaisiy padarthon ke ayatan tatha tadanuroop unake ghanatv par samany tap tatha dab parivartanon ka bahut prabhav padata hai. yadi dravyaman () dravyaman ki kisi gais k paramatap (0) par ayatan (0) hai to usi matra ki gais ka kisi any paramatap (1) tatha dab (1) par ayatan (1) ho jata hai. gaisiy niyamon ki sahayata se (1) tatha (0) ka nimnankit parasparik snbndh vyakt kiya ja sakata hai :

1 = 0

at: paribhasha ke anusar (1) tap evn (1) dab par gais ke ghanatv (1) tatha (0) tap evn (0) dab par ghanatv (0) men nimnankit snbndh prapt kiya ja sakata hai:

1 = 0

uparyukt samikaran ki sahayata se manak dab (0) tatha tap (0) par gais ka ghanatv gyat kar lene par kisi any tap tatha dab par bhi usaka ghanatv gyat kiya ja sakata hai. 0° sentigred tatha 760 milimitar pare ki dab ko kramash: manak tap tatha dab manate hain.

gaison ka apekshik ghanatv, usi tap tatha dab par, manak gais ke ghanatv ki tulana se vyakt karate hain. haidrojan ya vayu hi manak gaison ke roop men prayukt hoti hain.

samanyat: sabhi padarthon ka ghanatv tap badhane se ghatata tatha dab badhane se badhata hai. tap badhane ke sath pani ke ghanatv ka parivartan asadharan hota hai. 4° sentigred par pani ka ghanatv adhikatam hota hai. isase adhik tatha kam tap par pani ka ghanatv kam ho jata hai. pahale kaha ja chuka hai ki ghanatv padarthon ka vishesh gun hota hai. at: padarth ki shuddhata ka anuman usaka ghanatv gyat karake bhi kiya jata hai. isi adhar par doodh adi drav padartho ki shuddhata ke parikshak yntr banae ge hain.

padarthon ke ghanatv snbndhi gyan ka upayog arkimidiz ke siddhant ke anusar drav sthaitiki men kiya jata hai. isake anusar yadi vastu ko pahale vayu tatha phir drav men tola jay to donon bharon men antar vastu ke barabar ayatan ke drav ke barabar hota hai. is siddhant ki sahayata se padartho ka apekshik ghanatv nikala jata hai.

tatvon ke paramanu bhar tatha unake ghanatv ke anupat ko tatv ka paramanu ayatan kahate hain. is paramanu ayatan ke adhar par avart sarani men tatvon ke sthan ka nirdharan karane men bahut sahayata mili hai.

ghanatv avastha par nirbhar

padarthon ka ghanatv
padarth avastha tap dab ghanatv (gram prati ghan sentimitar)
jal (vashp) gais 100° sentigred 760 milimitar 5'81 x 10-4
vayu gais 37° sentigred 760 milimitar 1'93 x 10-3
jal (shuddh) drav 4° sentigred 760 milimitar 0.999
jal (samudri) drav 0° sentigred 760 milimitar 1.03 to 1.07
lakadi (sookhi) thos 20° sentigred 760 milimitar 0.4-0.8
kagaz thos 20° sentigred 760 milimitar 0.7-1.15
barf thos 0° sentigred 760 milimitar 0.917
shisha (sadharan) thos 20° sentigred 760 milimitar 2.4-2.8
kark thos 20° sentigred 760 milimitar 0.22 to 0.26
stil thos 20° sentigred 760 milimitar 6.9-8.9
ailuminiyam thos 20° sentigred 760 milimitar 2.64-2.82
tanba thos 20° sentigred 760 milimitar 8.96
pital thos 20° sentigred 760 milimitar 8.67-8.80
chandi thos 20° sentigred 760 milimitar 10.5
para thos 20° sentigred 760 milimitar 13.546
sona thos 20° sentigred 760 milimitar 19.3
any mahattvapoorn ghanatv
nam ghanatv (gram prati ghan sentimitar)
nabhik 2X1014
sabase adhik ghana tatv thos aausamiyam 22.8
prithvi (ausat) 5.517
chndrama (ausat) 3.341
soory (ausat) 1.41

kisi padarth ka ghanatv nikalane ki upayukt vidhi usaki thos, drav ya gais avastha par nirbhar karati hai. yahan par in vidhiyon ka snkshipt vivaran diya jayaga.

padarth ka ghanatv nikalane ke liye usaka bhar tatha ayatan gyat karana hota hai tatha apekshik ghanatv gyat karane ke liye usi ayatan ke manak drav ka bhi bhar gyat karana hota hai. padarth ka bhar to sugrahi tula dvara gyat kiya ja sakata hai. ayatan gyat karane ke liy ek chihnit jar men aisa drav lete hain jisamen padarth ghulata nahin hai. padarthapind ko drav men poori tarah duba dene par, drav ke ayatan men jitana parivartan ho vahi us padarthapind ka bhi ayatan hota hai. ghanatv ka adhik yatharth man gyat karane ke liye ayatanamapan ki adhik sugrahi vidhiyon ka upayog kiya jata hai, jaise ayatanamapi arthath‌ steriaaumitar[2] ka upayog.

ek samany ayatanamapi men, pare se bhari huee chaude munh ki ek nali men saman anuprasth kat ki shishe ki chihnit doosari nali hoti hai. doosari nali ki lnbaee pahali se chhoti hoti hai tatha usaka oopari sira ek pyale ke pende men khulata hai. pyale ko dhakkan se bnd kar dene par vayu bhi pyale ke bhitar ya bahar nahin ja sakati. doosari nali par do chihn k evn kh, lo (0) doori par bane hain. sarvapratham bairomitar se vayumndal ki dab () napate hain. ab dhakkan ko hatakar doosari nali ko itani nichi karate hain ki usake andar ka para k chihn tak a jay. tatpashchath‌ dhakkan bnd karake nali ko itana uthate hai ki doosari nali ke andar para kh sthan par ho jay. is samay nali ke andar pare ke tal ki, nali ke bahar pare ke tal se, oonchaee (0) gyat kar lete hain. isi vidhi ko pyale men padarthapind ko rakhakar doharate hain. yadi is samay doosari nali ke andar tatha bahar pare ke talon ka antar () ho, to nimnankit sootr dvara padarthapind ka ayatan gyat kar lete hain:

= -

yahan () padarthapind ka ayatan hai tatha () doosari nali ki anuprasth kat ka kshetraphal hai. is prakar kisi die hue padarth ka yatharth ayatan gyat kar lete hain.

drav padarthon ka apekshik ghanatv

drav padarthon ka apekshik ghanatv, ya ghanatv, apekshik-ghanatv-botal ki sahayata se nikala jata hai. ghanatv gyat karane ke liye pahale khali botal ki matra (0) gyat karate hain, tatpashchath‌ use drav se bhar kar usaki matra (1) gyat kar lete hain. drav bharakar dat lagane par kuchh drav keshikanali se bahar nikal jata hai, is prakar botal ka poora-poora ayatan drav se bhar jata hai. drav ka ghanatv (0) nimnalikhit sootr dvara maloom ho jata hai:

=

jabaki (0) botal ka ayatan hai, jise gyat ka ghanatv ke drav ki sahayata se gyat kiya jata hai. yadi botal ko doosari bar manak drav se bharakar matra (2) gyat kar len, to apekshik ghanatv (.) nimnalikhit prakar se gyat kar sakate hain:

..1 =

apekshik ghanatv botal ki sahayata se choore ya chhote-chhote tukadon ke roop men prapt, thos padartho ka ghanatv bhi nikala ja sakata hai. arkimidiz ke siddhant ki sahayata se bhi thos padartho ka apekshik ghanatv nikala ja sakata hai. yadi thos padarthapind manak drav men aviley tatha adhik ghanatvavala ho aur thos ki vay men matra (1) tatha phir manak drav men poora-poora dubakar usaki matra (2) ho, to padarth ka apekshik ghanatv:

..1 =

drav se kam ghanartav ke padarthon ka apekshik ghanatv uparyukt vidhi ka parivartan karake gyat kar sakate hain.

gaisiy padarthon ka apekshik ghanatv

viktar mayar ka upakaran

gaisiy padarthon ka ghanatv gyat karate samay unake tap tatha dab ka bhi nirikshan kiya jata hai. poorvokt sootr ki sahayata se kisi bhi tap tatha dab par gyat ghanatv se manak dab tatha tap par ghanatv gyat kiya ja sakata hai. gaisiy padarthon ka ghanatv gyat karane ki do mukhy vidhiyan hain:

  • reno ki vidhi:- is vidhi dvara un padarthon ka ghanatv gyat kiya ja sakata hai jo samany dab tatha tap par gaisiy avastha men rahate hain.

barabar ayatan tatha bhar ke do phlaskon ko atinirvat pamp ki sahayata se vayushoony kar ek sugrahi tula ke paladon ke niche lataka dete hain. ye phlask ek baks men rahate hain, jisaka tap sthir rakha jata hai. ab paladon par upayukt bhar rakhakar tula ko sntulit kar dete hain. tatpashchath‌ ek phlask ko gyat dabav d par gais se bhar dete hain. phlaskon ko yathasthan latakane par yadi ab tula ko () gram matra dvara sntulit karen to () tap tatha () dab par gais ka ghanatv = [=/] hoga. yahan () phlask ka ayatan hai. ise phlask ko gyat ghanatv ke drav se poora-poora bharakar tatha drav ka bhar gyat kar maloom kar sakate hain. gaisiy padartho ka apekshik ghanatv haidrojan ko manak manakar gyat kiya jata hain. uparyukt prayog ko yadi haidrojan ke sath doharane par usaki matra (0) gyat ho to uparyukt gais ka apekshik ghanatv = /0

  • viktar mayar ki vidhi:- is vidhi ka upayog adhik tap par gais banane vale padarthon ke vashp ka ghanatv gyat karane men kiya jata hai. niche upakaran chitrit hai. phlask ph men aisa padarth d2 liya jata hai jisaka kvathanank padarth d ke (jisake vashp ka ghanatv gyat karana hai) kvathanank se adhik ho. phlask ph ko garam karate hain. nali n men padarth d ki gyat matra m () rakh dete hain. nali n se ek patali nali ek chihnit nali ch men khulati hai, jo drav d1 se bhari hoti hai. d1 aisa drav hota hai jisake sath padarth d ka vashp koee prakriya nahin karata. garam hone par padarth d vashp roop ho jata hai. isaka vashp nali n men bhar jata hai. yah vashp apane ayatan ke anusar vayu ke nali n se ch men nikal deta hai. isi ayatan a () ka dr ch ke bahar a jata hai, jo chihnit nali men drav d1 ki satah ke parivartan se gyat hota hai. yadi drav d1 ka ka tap ta1 (1) tatha yadi samany tap par d1 ki vashpadab va1 (1) hai, to (va-va1) [-1]

dabav par tatha ta1 (1) tap par uparyukt padarth ke vashp ka bhar m1 () hoga, jab va1 () vayumndal ki dab hai. at: manak dab tatha tap par vashp ka ghanatv gh () nimnankit hota hai :

=


panne ki pragati avastha
adhar
prarambhik
madhyamik
poornata
shodh

tika tippani aur sndarbh

“khand 4”, hindi vishvakosh, 1964 (hindi), bharatadiskavari pustakalay: nagari pracharini sabha varanasi, 107-110.

  1. C. G. S.
  2. stereometer

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