Ohm's Law Aur Resistance 📈

Ek Bahut Seedha Rishta 🔗

1827 mein ek german school teacher, Georg Simon Ohm, ne ek bahut hi saada prayog kiya. Unhone ek taar par voltage badhaya aur har baar current naapa.

Aur unhe ek bilkul seedha pattern mila: voltage dugna karo, current bhi dugna. Teen guna karo, current bhi teen guna. Har baar.

📌 Ohm ka niyam: ek fix taapmaan par, kisi conductor mein bahne wala current uske sire par lage potential difference ke seedhe ratio (anupaat) mein hota hai.

V = I R

Yahan R ek sthirank hai jise resistance kehte hain.
Ikai: ohm (Ω).   1 Ω = 1 volt / 1 ampere

😔 Ohm ko unke zamaane mein nakaara gaya

Aaj ye niyam har kitaab mein hai. Par jab Ohm ne 1827 mein ise chhapa, toh german vaigyanikon ne ise "bekaar aur bachkana" kehkar thukra diya. Ek bade professor ne toh kaha ki jo aisa likhta hai wo "padhane ke laayak nahi".

Ohm ko apni school ki naukri tak chhodni padi aur wo kai saal gareebi mein rahe.

Par dheere-dheere doosre desh ke vaigyanikon ne unka kaam padha aur maana. 1841 mein — 14 saal baad — London ki Royal Society ne unhe apna sabse bada samman Copley Medal diya. Aur aaj resistance ki ikai ka naam hi "ohm" hai.

Sabak: sahi kaam ko pehchaan milne mein waqt lag sakta hai — par milti zaroor hai.

📈 V-I Graph — Seedhi Rekha Ka Matlab

Current I (ampere) → Voltage V (volt) → 12 34 24 68 R = 2 Ω kam dhaal = kam resistance R = 4.5 Ω zyada dhaal = zyada resistance ΔI = 1 ΔV = 2 Graph ki DHAAL = R R = ΔV / ΔI = 2/1 = 2 Ω
V-I graph hamesha ORIGIN se guzarti SEEDHI rekha hota hai. Uski dhaal hi resistance hai — jitni khadi rekha, utna zyada resistance.

📌 Graph se teen baatein saaf ho jaati hain:
1️⃣ Rekha seedhi hai → V aur I ka rishta seedha ratio wala hai
2️⃣ Rekha origin (0,0) se guzarti hai → voltage zero toh current bhi zero
3️⃣ Rekha ki dhaal = R → jitni khadi rekha, utna zyada resistance

⚠️ Agar graph seedhi rekha na ho, toh wo cheez Ohm ka niyam nahi maanti — jaise bulb ka filament (garam hone par uski resistance badh jaati hai) ya diode.

🚧 Resistance Asal Mein Hai Kya?

Resistance = current ke bahne ka virodh. Par ye virodh aata kahan se hai?

📌 Taar ke andar electrons aage badhte waqt metal (dhaatu) ke atoms se takraate rehte hain. Har takkar mein wo thodi energy khote hain — aur wo energy garmi ban jaati hai.

Jitni zyada takkarein, utna zyada virodh, utna zyada resistance — aur utni zyada garmi.

Yahi wajah hai ki heater aur bulb garam hote hain. Resistance sirf ek rukaawat nahi — wo bijli ko garmi mein badalne ka zariya bhi hai.

🏃 Bheed wali gali wali soch

Ek khali gali mein daudna aasaan hai — kam resistance.

Ab wahi gali bheed se bhari ho. Aap har do kadam par kisi se takra jaate hain, ruk-ruk kar chalte hain, aur garam ho jaate hain — zyada resistance.

Aur garmi mein? Atoms aur zyada hilte hain, isliye takkarein aur badh jaati hain — isiliye garam taar ki resistance zyada ho jaati hai. Yahi wajah hai ki bulb ke filament ka V-I graph seedhi rekha nahi hota.

PrakaarResistanceUdaharan
ConductorBahut kamCopper, aluminium, silver, chaandi
ResistorMadhyam / khaasNichrome, manganin, carbon
InsulatorBahut zyadaRubber, plastic, kaanch, lakdi
SuperconductorBilkul zero!Kuch metals, bahut thande par

🧮 Hal Kiye Hue Sawaal

📝 Sawaal 1 — Current Nikaalo

Ek 3 Ω ke resistor par 6 V lagaya gaya. Current kitna bahega?

Hal: V = IR  →  I = V/R
I = 6 / 3 = 2 A

📝 Sawaal 2 — Resistance Nikaalo

Ek device par 4 V lagane par 0.2 A current bahta hai. Uski resistance kitni hai?

Hal: R = V/I
R = 4 / 0.2 = 20 Ω

📝 Sawaal 3 — Voltage Nikaalo

Ek 20 Ω ke resistor mein 0.5 A current bah raha hai. Uske sire par kitna voltage hai?

Hal: V = IR
V = 0.5 × 20 = 10 V

📝 Sawaal 4 — Ghar Wala Udaharan

Ek electric bulb 220 V ki supply par chalta hai aur uski resistance 44 Ω hai. Usme kitna current bahega?

Hal: I = V/R = 220 / 44 = 5 A

💡 Isi 5 A ko dekh kar tay hota hai ki us line mein kitne ampere ka fuse lagana chahiye.

📝 Practice — Khud Karo

(a) V = 12 V, R = 4 Ω. I = ?
Jawab: I = 12/4 = 3 A

(b) V = 3 V, R = 15 Ω. I = ?
Jawab: I = 3/15 = 0.2 A

(c) Ek taar mein 2 A par 10 V hai. Agar voltage 25 V kar dein toh current?
Jawab: pehle R = 10/2 = 5 Ω. Phir I = 25/5 = 5 A

⚠️ Numericals ki 3 aam galtiyan:
1️⃣ Formula ulta laga dena — yaad rakho V = IR, isse I = V/R aur R = V/I dono nikal aate hain
2️⃣ mA ko A mein nahi badalna — 500 mA = 0.5 A
3️⃣ kΩ ko Ω mein nahi badalna — 2 kΩ = 2000 Ω

🇮🇳 India Connection

Bharat mein bijli ke taar zyadatar aluminium ke hote hain, jabki ghar ki wiring copper ki. Kyun?

Copper ki resistance kam hai (behtar), par wo bhaari aur mehnga hai. Bijli ke lambe khambon wale taar ke liye halka hona zyada zaroori hai — isliye wahan aluminium chalta hai, chaahe uski resistance thodi zyada ho.

Ghar ke andar lambai kam hai, isliye wahan copper ka faayda le liya jaata hai.

⚠️ Aur ek zaroori baat: kai jagah log paise bachane ke liye patle aur kam quality ke taar lagwa lete hain. Patla taar = zyada resistance = zyada garmi — aur yahi short circuit se aag lagne ka sabse bada kaaran hai. Ye chapter samajhne ke baad aap ye galti kabhi nahi karoge.

🧠 Apne Aap Ko Test Karo

Q1. Ohm ka niyam kya kehta hai?
Q2. V-I graph ki DHAAL (slope) kya batati hai?
Q3. V = 12 V aur R = 4 Ω hai. Current kitna hoga?
Q4. Resistance asal mein kis wajah se hoti hai?
Q5. Ek device par 4 V lagane par 0.2 A bahta hai. Resistance?
Q6. Bulb ke filament ka V-I graph seedhi rekha kyun nahi hota?

📈 Graph Explorer mein voltage badhao aur V-I rekha ko banta dekho!

Open Graph Explorer →
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