1.3.10 · D1Efficiency
Har real machine energy andar leta hai aur tumhe kam useful energy wapas deta hai, kyunki kuch energy hamesha heat, sound aur friction ke roop mein leak ho jaati hai. Efficiency bas ek score hai — jo tumne daala uska kitna fraction kaam ka kaam karte hue nikla.
Pehle tumhe parent note Efficiency ko use karna hai, toh usmein aane wala har symbol bilkul obvious feel hona chahiye. Yeh page har ek ko bilkul zero se build karta hai — ek picture, plain-words meaning, aur kyun topic ko yeh chahiye — ek aisi order mein jahan har idea pehle waale par tikaa ho.
E Energy ek machine ki "kuch karne ki ability" hai — ek box uthana, ek wheel ghumana, light banana. Hum ise joules mein measure karte hain (symbol J
Ek pani ka bucket imagine karo. Pani ki matra = energy ki matra. Tum ise daal sakte ho, split kar sakte ho, idhar-udhar move kar sakte ho — lekin (yeh hi key rule hai neeche) tum kabhi bhi extra pani kahin se bana nahi sakte.
Intuition Topic ko yeh kyun chahiyeEfficiency jo energy mili aur jo energy di unhe compare karti hai. Agar tumhare paas energy ka ek clear picture nahi hai as a countable, pourable quantity, toh ratio ka koi matlab nahi.
Bucket figure dekho: pani ka level E compare kar sakte hain — yahi comparison poora game hai.
Energy ko pieces mein split karne se pehle, humein har piece ko name karne ka ek tarika chahiye. Physicists ek chhota sa neeche ka tag lagate hain.
Subscript ek chhota sa tag hota hai jo kisi symbol ke neeche likha jaata hai jo batata hai ki hum woh particular wala kaunsa mean kar rahe hain. Yeh ek label hai, multiplication nahi . Toh E in andar gayi", aur E out bahar aayi". Yeh sab energies hain (sab joules mein), bas alag-alag dher hain.
E in E × i × n Fix: subscripts kabhi multiply nahi karte. Inhe surnames ki tarah socho — same family (energy E
Ab humare paas tools hain (E
Definition Conservation of energyEnergy kabhi create ya destroy nahi hoti — yeh sirf form change karti hai. Jo bhi amount ek machine mein jaati hai woh wapas zaroor aati hai, bas possibly alag costume mein (motion ki jagah heat, maano).
Parent note ka leaky bucket imagine karo. Tum upar se pani daalo. Woh do chhedon se nikalti hai: neeche ka useful spout, aur sides mein leaks. Sides mein wala pani gayab nahi hua — woh floor par hai. Spout-water + floor-water jodo aur tumhe exactly wahi milega jo tumne daala tha. Apne subscript tags use karke:
jo daala E in = spout E useful + leaks E wasted
Intuition Topic ko yeh kyun chahiyeYeh single equation woh skeleton hai jis par parent note efficiency build karta hai. "Kuch bhi gayab nahi hota" ke bina, ek machine magically jo liya usse zyada output de sakti thi, aur 100% se zyada efficiency allow ho jaati. Yeh rule ise forbid karta hai.
Poora law dekhne ke liye Conservation of Energy refer karo.
Is figure mein total poured-in arrow (magenta) ek useful arrow (orange) aur ek wasted arrow (violet) mein split hoti hai. Woh hamesha input mein wapas jodte hain — yahi conservation arrows ki tarah draw hua hai.
E useful Useful energy output ka woh hissa hai jo exactly woh kaam karta hai jo tum chahte the . Aur kuch count nahi hota, chahe woh kitna bhi real ho.
E wasted Wasted energy har woh doosri form hai jismein input change ho gayi jo tumhe nahi chahiye thi — usually heat, sound, vibration.
Common mistake "Wasted energy destroy ho jaati hai."Kyun aisa lagta hai: heat nazar nahi aati, toh lagta hai chali gayi.
Fix: yeh floor par wala pani hai — abhi bhi wahan hai, bas spout mein nahi. E wasted bookkeeping label hai, deletion nahi.
Intuition Topic ko yeh kyun chahiyeEfficiency ki top line useful out hai, total out nahi. Ek light bulb light aur heat output karta hai; sirf light useful hai. Yeh split sahi karna exam ka sabse common trip-up hai.
Heat and Internal Energy dekho (waste usually heat ban jaati hai) aur Friction (leak ka ek top cause).
Definition Ratio / fractionEk fraction b a "b a ya equivalently "a b Bar ka matlab hai "upar waale ko neeche waale se divide karo".
Do buckets imagine karo. Useful bucket mein 300 units hain, input bucket mein 500. Fraction 500 300 useful bucket kitna full hai us cheez ke comparison mein jo tumne pay kiya .
E in E useful = 500 300 = 0.6
Ratio kyun aur subtraction kyun nahi?
Hum gap E in − E useful = 200 J ratio sizes mein fair hai: yeh hamesha 0 aur 1 ke beech rehta hai chahe machine kitni bhi badi ho, toh hum ek phone charger ko ek rocket se same scale par compare kar sakte hain. Yahi wajah hai efficiency ek ratio ki tarah define ki gayi hai.
η η "ee-ta" ) bas woh naam hai jo physicists us useful-over-input ratio ko dete hain. η E in E useful η = E in E useful
Ek dimensionless number ki koi units nahi hoti — upar ke joules neeche ke joules se cancel ho jaate hain. 500 J 300 J = 0.6
Percent ka matlab hai "per hundred". Fraction ko percentage mein convert karne ke liye, 100 % 0.6 → 60%
Ek ruler imagine karo jis par ek end par 0 marked hai aur doosre par 1. Har real machine ka η 0 aur 1 ke beech kahin ek mark hai — kabhi 1 se aage nahi. Neeche hum dekhenge kyun 1 ek wall hai.
Number line figure: 0 = bilkul useless (sab leaks), 1 = perfect (impossible), aur real machines shaded middle mein rehti hain. 1 par laal wall conservation of energy hai jo keh rahi hai "aage nahi".
Intuition Yahan har case kyun matter karta hai
η = 0 saari input waste (ek machine jo zero useful work karti hai — e.g. ek spinning wheel jisme load disconnect ho).0 < η < 1 η = 1 η > 1 forbidden — matlab hoga jo daala usse zyada pani nikla.
t t time ke liye stand karta hai — koi process kitne seconds tak chali. Unit: second (s
P Power energy per unit time hai — energy kitni fast flow karti hai. Unit: watt (W 1 W = 1 J per second P = t E
Bucket ko phir imagine karo lekin ab flow rate dekho — litres per second spout se — total litres ki jagah.
Intuition Topic ko dono forms kyun chahiyeKuch questions tumhe energies (joules) dete hain, kuch powers (watts). Kyunki input aur output same time t t η = E in / t E useful / t = P in P useful Work and Power dekho.
Kaafi efficiency problems mein kuch uthaya jaata hai, aur useful energy woh height gained hoti hai. Lekin kyun woh energy exactly m g h
Intuition Energy force pushed through a distance haiEk box uthane ke liye tumhe upar gravity ke pull se thoda zyada force se push karna hoga. Physicists jo energy tum spend karte ho use measure karte hain as force × — jitna zyada push karo aur jitni door push karo, utni zyada energy spend hoti hai. Woh product F × d Work and Power ).
Definition Weight — gravity ka downward pullEk mass ==m m × g g ≈ 10 m/s 2 weight hai.
Ab picture assemble karo: box ko steadily uthane ke liye tum upar push karte ho iske weight m g h ×
E = force jo tum lagate ho ( m g ) × kitna uthaya h = m g h
Definition Gravitational potential energym g h E = m g h Gravitational Potential Energy .
Figure mein orange arrow upar ki push hai (size m g h m g h
Worked example Parent ke Example 1 ko nayi nazar se padhna5 kg 6 m = m g h = 5 × 10 × 6 = 300 J = 500 J η = 500 300 = 0.6 = 60% har symbol ke peeche ek picture hai.
Right side cover karo aur khud ko test karo. Agar koi bhi answer surprise kare, woh section dobara padho.
Symbol E Energy, joules mein measure hoti hai (J
E in Yeh ek subscript hai (ek label), multiplication nahi.
Conservation of energy ek line mein batao. Energy kabhi create ya destroy nahi hoti, sirf form change hoti hai; input, useful plus wasted ke barabar hoti hai.
Useful aur wasted energy mein kya fark hai? Useful woh part hai jo woh kaam karta hai jo tumhe chahiye tha; wasted har doosri form hai (heat, sound), abhi bhi conserved hai lekin unwanted.
Efficiency ratio kyun hai aur subtraction kyun nahi? Ratio machine sizes mein fair hai aur hamesha 0 aur 1 ke beech rehta hai, toh machines comparable hain.
Efficiency ko kaunsa Greek letter symbolise karta hai aur ise kaise padha jaata hai? η
Efficiency dimensionless kyun hai? Upar aur neeche ke joules cancel ho jaate hain, ek pure number reh jaata hai.
η = 0.6 0.6 × 100 = 60%
t Time, seconds mein measure hota hai (s
Efficiency ka power form likho aur batao kyun t η = P useful / P in t
Lifted load ki useful energy force times distance se derive karo. Force m g h = m g × h = m g h
η Conservation forbid karta hai jo andar gaya usse zyada energy bahar aaye; "1" ek wall hai.
