paraashravya

paraashravya (ultrasound) shabd us dhvani ke liye upayog mein laaya jaata hai jiski aavrutti itni adhik hoti hai ki vah manushya ke kaanon ko sunaai naheen deti. saadhaaranataya maanav shravanashakti ka paraas 20 se lekar 20,000 kanpan prati second tak hota hai. isliye 20,000 se adhik aavruttivaali dhvani ko paraashravya kehte hain. arvaacheen vidhiyon dvaara ab lagbhag 109 kanpan prati second waali paraashravya dhvani ka utpaadan sambhav ho gaya hai. kyonki mote taur par dhvani ka veg gas mein 330 meter prati sein., drav mein 1,200 mi. prati sein. tatha thos mein 4,000 mi. prati se. hota hai, ataev paraashravya dhvani ka tarangadairdhya saadhaaranataya 10 - 4 seinmi. hota hai. iski sookshmata prakaash ke tarangadairdhya ke tulya hai. apni sookshmata ke hi kaaran ye tarangein udyog dhandhon tatha anveshan kaaryon mein ati upayukt siddh hui hain aur aajkal inka mahatva atyadhik badh gaya hai.

neeche ke chitr mein apashravya (infrasound), shravya (audible) aur paraashravya (ultrasound) tarangein aur unki aavrutti ka paraas (range) dikhaaya gaya hai :

iski nimnalikhit vidhiyaaain hain :

yaantrik janitr

1899 E. mein koning ne chhote chhote svaritron dvaara 90,000 kanpan prati sein., tak ki paraashravya tarangein utpann keen. idemaan ne gaaltan seeti ko banaaya, jiske dvaara vah ek nishchit aayaamavaale 1,00,000 kanpan prati se. utpann karne mein safal hua. ek tund mein se hava fooainki jaati hai. hava ki yeh dhaara ekadeergh chhidr mein se bahakar ek kshuradhaar se takaraakar paraashravya kanpan paida karti hai. gas-dhaara janitr dvaara haartamaan ne adhik oorjaavaali paraashravyadhvani paida ki. haufamaan ne kaach ki chhad ko usaki lanbaai ki samaantar disha mein kanpit kar 33,000 kanpanavaali adhik oorja ki paraashravya dhvani utpann ki.

vidyujjanitr

ab inka keval aitihaasik mahatva hai. atabarg ne sfuling-antaraal (spark gap) dvaara 3,00,000 aavruttivaali paraashravya dhvani paida ki, kintu yeh dhvani kai bhinn bhinn aavruttiyon ka mishran hoti hai aur inka aayaam bhi anishchit hota hai.

chunbakeeya aakaaraantar janitr (Magneto-striction Generator)

yadi lohachunbakeeya (ferromagnetic) padaarth ki chhad athva nali ko usaki lanbaai ke samaantar kisi chunbakeeya kshetr mein rakha jaae to aanvik punarvyavastha ke kaaran usaki lanbaai mein parivartan ho jaata hai. is ghatna ko chunbakeeya aakaaraantar kehte hain. yeh anusandhaan jool ne kiya tha. lanbaai ka yeh parivartan chunbakeeya balakshetr ki disha par nirbhar naheen hai. yadi koi lohachunbakeeya padaarth pratyaavarti chunbakeeya kshetr par rakha jaae to vah apni svaabhaavik athva adhisvar aavrutti se kanpit hokar paraashravya dhvani utpann karega.

chunbakeeya shaithilya (hysterisis) ke kaaran vidyuchchunbakeeya oorja ka paraashravya oorja mein parivartan adhik achha naheen hota hai. saath hi, is vidhi mein padaarth ko valaya ke roop na le sakane ke kaaran adhiktam aavruttivaali paraashravya dhvani utpann naheen ki ja sakti.

Vincent aur peears, donon mein chunbakeeya akaaraantar dvaara paraashravya kanpan paida karne ke liye vidyuteeya paripth banaae. yeh paripth chunbakeeya aakaaraantar ke vyutkram prabhaav ke kaaran, svat: uttejit vidyuteeya dolan utpann karta hai, kyonki chhad ki lanbaai ki pratyaasth ghat badh chunbakan mein parivartan kar deti hai aur isse prerit vidyudvaahak bal grid ke dvaara dhanaagr ki dhaara ko niyantrit karta hai.

is vidhi ka mukhya laabh iski saadagi evam sastepan mein hai tatha ismein truti hai taap par nirbhar rahana aur aavrutti ka adhik na rahana.

is vidhi se adhiktam aavrutti 200000 tak utpann ki ja sakti hai.

daab-vidyut‌ (piezo-electric) janitr

san‌ 1880 mein pi. aur pi.J. kyoori ne bataaya ki yadi samamiti rahit sfatikon ya kristalon ke kinheen vishesh akshon par dabaav lagaaya jaae to unke do talon par vijaateeya vidyudaavesh utpann hote hain. kuchh dinon baad inheen do bhaaiyon ne isse vipreet prabhaav ka bhi aavishkaar kiya, arthaat‌ yeh pramaanit kiya ki bal lagaane se in kristalon ki lanbaai mein parivartan hota hai. is ghatna ko daab-vidyut‌-prabhaav kehte hain. san‌ 1917 E. lainjevin ne kvaartj kristal ko usaki svaabhaavik aavrutti se kanpit karne ke liye ek samasvarit vidyut‌ paripth ke dvaara use uttejit kiya. yadi vidyut‌ paripth ki aavrutti kristal ki aavrutti ke baraabar ho, jo kristal anunaadit kanpan karne lagta hai. kristal apni svaabhaavik aavrutti ki adhisvarit aavrutti tatha nishchit aayaamavaali paraashravya dhvani utpann karta hai. paraashravya dhvani utpann karne ki yahi arvaacheen vidhi hai.

kvaartj ke atirikt toormailin, taartarik aml, roshel lavan, beriym taaitainet ityaadi ka bhi dolak banaane mein upayog hota hai. upayukt aakaar ke kristalon se ya to unki svaabhaavik aavrutti, athva vishay sannaadi (harmonics), utpann karke 2v 104 se lekar 2v 108 tak ki aavruttivaali paraashravya dhvani utpann ki jaati hai.

haartale ka vidyut‌ paripth kristal kanpit kiya jaata hai. paripth ke sandhaaritr ke maan ko samaanjit kar samasvarit kiya jaata hai. is paripth ke atirikt aur bhi anya paripthon ka vibhinn kaaryon ke liye paraashravya dhvani utpann karne mein upayog kiya jaata hai.

kristalon ko kaam mein laane se poorv vishesh reeti se kaata jaata hai aur unako prayog ke liye vishesh reeti se rakha jaata hai.

paraashravya dhvani ke mukhyat: chaar prakaar ke parichaayak hote hain :

yaantrik parichaayak

jab gas maadhyam mein bilkul halake thos, athva drav, ke kan chhode jaate hain tab ve paraashravya dhvani ke dvaara apne avasthititv ke anusaar chaalit hote hain. unki gati ke adhyayan se paraashravya dhvani ka parichay praapt hota hai.

ainthan lolak athva vikirnamaapi (radiometer) se bhi paraashravya tarangon ka gyaan hota hai. ek vishesh yantr ke mandalak par ye tarangein girkar, usapar daab daalkar use ghumaati hain. mandalak ka ghoomana uske aalanbanasootr mein lage darpan ke dvaara naapa jaata hai.

yadi paraashravya tarangein ati sookshm na hon to kunt ki nali mein agragaami tarangein banaakar laaikopodiym choorn dvaara unka prekshan kiya jaata hai.

ushmeeya parichaayak

dhvanigraahi deepashikha (sensitive flame) dvaara dhvani ki tarangon ke hi samaan in tarangon ka bhi parichay praapt kiya jaata hai.

ye tarangein taaron par girkar kramash: ushma athva sheet paida karti hain. taap ke is parivartan se taar ka vidyut‌ pratirodh badalta hai. is gun ka bhi upayog in tarangon ke baare mein gyaan praapt karne mein hota hai.

prakaashit parichaayak

paraashravya tarangon se jo apragaami tarangein banti hain, unase maadhyam ka vartanaank kaheen badh jaata hai aur kaheen ghat jaata hai. is prakaar ke maadhyam mein se prakaash ke jaane par rekhaankan (striation) ho jaata hai. in rekhaaon ke gyaan se in tarangon ka parichay hota hai. pragaami tarangein bhi stroboskopi pradeepan (stroboscopic illumination) ke dvaara isi vidhi se vyakt ho jaati hai.

vaidyut parichaayak

beriym taaitenet ke kristal ke daabavidyut‌ gun ka upayog kar usase maaikrofon banaaya jaata hai aur uske dvaara in tarangon ka astitv maaloom kiya jaata hai.

1. paraashravya aavruttidrshi - paraashravya tarangon dvaara maadhyam mein jo greting (grating) banta hai, usamein se jaanevaale ekavarn prakaash ki teevrata vibhinn dishaaon mein vibhinn parimaan ki ho jaati hai. is teevrata vitran ke dvaara aavrutti ki naap ho jaati hai.

2. dooraveekshan (Television) - dooraveekshan ki skofoni vyavastha mein is dhvani ka upayog hota hai.

3. padaarthon ka pareekshan - saadhaaranataya shuddh dhaatuon mein paraashravya tarangon ka sancharan vikaaraheen hota hai, kintu unamein yadi kaheen toot foot ho, athva sammaangita na ho, to vahaaain par in tarangon ka paraavartan athva avashoshan ho jaata hai. is prakaar sancharan mein gadbadi hone se truti ka pata chal jaata hai. isi vidhi ka upayog mastishk ke tyoomar, athva Cancer, jaisi beemaari ka pata lagaane mein bhi hone laga hai.

4. pratidhvani paraasan - inse pratidhvani paraasan ka kaam bhi liya jaata hai. panadubbiyon dvaara kuhare evam dhundh mein plaavi himshail ka gyaan isi ke dvaara praapt kiya jaata hai. samudra ki gaharaai ki tatha anya jahaajon ki doori ki naap bhi isi vidhi se hoti hai.

5. vyaasaaran evam kalileekaran - paraashravya tarangon dvaara ek doosare mein pan ghulanevaale dravon ka paayas ban jaata hai. yahaaain tak ki in tarangon ke prabhaav se dhaatu bhi drav mein apna paayas banaati hain. fotograafi ke kaam mein aanevaala chaaaindi ka hailaaid bhi isi vidhi se banta hai. in tarangon ke prabhaav se uchchabahulak (polymer) anu toot jaate hain aur is prakaar staarch se sharkara banti hai. paraashravya dhvani ki paayaseekaran kriya ka upayog achhi dhaatu banaane ke kaam mein bhi hota hai. lohe mein naaitrojan ka niveshan bhi isse sugamataapoorvak hota hai.

6. apakshepan (coagulating) kriya - gas maadhyam mein thos evam drav ke chhote chhote kan paraashravya dhvani se apakshepit hokar jama ho jaate hain. is prakaar bade nagaron ke kal kaarkhaanon se niklanevaala haanikaarak dhuaaain nagar ke baahar jaane se roka jaata hai. theek isi prakaar kuhara tatha dhundh bhi door kiye jaate hain.

7. raasaayanik prabhaav - kai raasaayanik abhikriyaaon ka veg in tanragon ke kaaran badh jaata hai. lambi shrrunkhala vaale bahulakon ko isse toda bhi ja sakta hai.

8. ushmeeya prabhaav - paraashravya tarangon dvaara ushma ka upayog daayaatharmi (diathermy) mein hota hai. isse haddi ki majja ko bina haddi par prabhaav daale garam kiya jaata hai.

9. jaivik prabhaav - chhote praani, jaise machhali, medhak, protojoaa ityaadi in tarangon dvaara mar jaate hai. jeevaanuon mein inke prabhaav se parivartan ho jaata hai. inse doodh ko jeevaanurahit kar sakte hai. isse maans ko adhik dinon tak taaja rakh sakte hain tatha sharaab ka jeernan badhaaya ja sakta hai.

10. kuchh anya upayog - paraashravya dhvani se heere ko kaatne evam peshan ka kaam hota hai. kutton ko bulaane ke liye aisi seetiyaaain hain jinhein unki paraashravya dhvani ke kaaran ham sun naheen paate hain.

is prakaar in vividh upayogon ke kaaran is aanavik yug mein bhi paraashravya dhvaniki ka bhautik vigyaan mein mahatvapoorn sthaan hai.

• sonograafi ya paraashravya chitran

• altraasaaund se ghutne ke dard ka ilaaj
• Kundu, Tribikram. Ultrasonic nondestructive evaluation: engineering and biological material characterization. Boca Raton, FL: CRC Press, c2004. ISBN 0-8493-1462-3.
• Guidelines for the Safe Use of Ultrasound: valuable insight on the boundary conditions tending towards abuse of ultrasound.
• High-frequency hearing risk for operators of industrial ultrasonic devices:
• Safety Issues in Fetal Ultrasound:
• Damage to red blood cells induced by acoustic cavitation(ultrasound):