Time kaise naapte hain?

Prakriti ke clock

Bahut pehle logon ne dekha ki prakriti ki kai ghatnaayein tay antar ke baad dohraati hain: Sooraj ugta aur doobta hai, Chaand apni kalaayein badalta hai, aur mausam laut kar aate hain. Inhi chakron se unhone time ka hisaab rakha. Pehle Sooraj ke ugne aur doobne se tay din aur calendar aaye. Phir log din ke andar time jaanne ke tareeke dhoondhne lage.

Sundial, water clock, hourglass aur mombatti

• Sundial: Sooraj se bani kisi cheez ki parchhaai din bhar jagah badalti hai, aur scale pe uski jagah time batati hai.
• Water clock: ek tarah mein time ke nishaan waale bartan se paani baahar behta hai. Doosri tarah mein neeche baareek ched waala katora paani pe tairta hai, dheere-dheere bharta hai, aur tay samay ke baad doob jaata hai; phir use nikaal kar dobara tairaaya jaata hai.
• Hourglass: ret tay samay mein ek bulb se doosre mein behti hai.
• Candle clock: lakeeron waali mombatti; har hissa tay samay mein jalta hai.

Puraane India mein time naapna

Puraane India mein parchhaai aur water clock dono se time naapa jaata tha. Kautilya ka Arthashastra, jo 2nd century BCE aur 3rd century CE ke beech likha aur sudhaara gaya, parchhaai se time aur baahar paani nikalne waale water clock ka zikr karta hai. Lagbhag 530 CE mein Varahamihira ne khadi chhadi ki parchhaai se time ka sateek niyam diya. Baahar paani nikalne waale clock zyaada sateek nahi the, kyunki star girne pe paani dheere nikalta hai. Isse doobne waale katore ka clock, ghatika-yantra, bana, jise sabse pehle Aryabhata ne bataya. Iska katora 24 minute mein bharkar doobta tha, jise ghatika ya ghati kehte the, isliye 24 ghante ke din mein 60 ghati hoti thi. Ye maths, mahalon aur shahar ke chaukon mein chalta tha, jahan har baar katora doobne pe nagaade, shankh ya ghanta bajaaya jaata tha, jab tak late nineteenth century mein pendulum clocks ne iski jagah nahi li.

Jaipur ke Jantar Mantar ka Samrat Yantra, jo lagbhag 300 saal pehle bana, duniya ka sabse bada patthar ka sundial hai. Ye 27 m ooncha hai, iski parchhaai har second lagbhag 1 mm chalti hai, aur iska scale 2 second jitne chhote antar dikhata hai. Har sundial ki tarah ye local solar time dikhata hai, jise Indian Standard Time ke liye sudhaarna padta hai.

Ek water clock banao

Ek purani plastic ki botal ko do hisson mein kaato, drawing pin se dhakkan mein chhota ched karo, aur upar waale hisse ko ulta karke neeche waale hisse pe rakho. Upar rangeen paani bharo aur ghadi dekhkar har minute neeche waale hisse mein paani ka star mark karo. Istemaal karne ke liye paani waapas upar daalo: har baar star ek nishaan tak pahunche, to ek minute aur beet gaya.

Pendulum, quartz aur atomic clocks

Jab log lambi yaatraayein karne lage, to sahi time bahut zaroori ho gaya. Fourteenth century se mechanical clocks wazan, gears aur springs se chalne lage, aur 1656 mein Christiaan Huygens ne pendulum ke niyamit jhoole pe chalne waala pendulum clock banaaya (dekho simple pendulum kya hai). Aaj ke clocks yahi vichaar chhote, bahut tez kampanon ke saath istemaal karte hain: quartz clocks mein quartz crystal ke, aur atomic clocks mein kuch khaas atoms ke. Huygens ke shuruaati clock din mein 10 second aage ya peeche ho sakte the; atomic clocks laakhon saal mein sirf lagbhag ek second khote hain.

Second aur doosri units

Time ki SI unit second (s) hai. Badi units minute (min) aur hour (h) hain: 60 s = 1 min aur 60 min = 1 h. Unit ke naam aur nishaan chhote aksharon mein (vaakya ki shuruaat chhodkar) aur ekvachan mein likhe jaate hain, number aur nishaan ke beech space ke saath aur nishaan ke baad full stop ke bina. Isliye 5 s aur 2 h likho, kabhi 5 sec ya 2 hrs nahi. Seconds ki suyi waala deewaar ka clock sabse chhota 1 second ka antar naap sakta hai.

Kai kaamon ke liye isse bhi chhote antar chahiye. Race ki timing second ke sauvein ya hazaarvein hisse (millisecond) tak ka record rakhti hai, ECG heart monitor milliseconds ke badlaav naapte hain, aur phone aur computer microseconds, yaani second ke dus-laakhvein hisse, mein signals pe kaam karte hain.

Ye kyun zaroori hai

Sahi time hamari rozaana zindagi chalata hai, school ki ghanti aur train ki timetable se lekar khel, dawai aur antariksh khoj tak. Time se hi hum gati naap paate hain: padho speed aur uniform motion. Textbook ke sawaalon ke jawab Chapter 8 ke NCERT solutions mein hain; poore chapter ke liye Chapter 8 ke notes.