Define electric charge, electron, proton, and the coulomb

1.1.1 · Hardware › Electricity & Charge Basics

WHAT is electric charge?

WHY does this matter? Kyunki hardware ka poora behaviour — copper mein electrons ka flow, transistors ka switching — sirf charges ka ek doosre ko push aur pull karna hai.

Charge kyun exist karta hai, iska koi "gehri" explanation nahi hai; yeh physics ka ek primitive hai, jaise mass. Hum describe karte hain ki yeh kya karta hai, nahi ki yeh kis cheez se bana hai.

WHAT are the electron and proton?

WHY equal and opposite? Normal atom mein protons aur electrons ki sankhya barabar hoti hai, isliye atom neutral hota hai (net charge zero). Ek electron remove karo → atom ab positive ho jaata hai (ek ion). Yahi exact balance ki wajah se bulk matter aam taur par neutral hota hai, aur isliye wire mein current electrons ke move karne se hoti hai (protons se nahi).

WHAT is the coulomb?

WHY define a unit at all? "Kitna charge?" ke liye ek number aur ek unit chahiye, bilkul waise jaise "kitna paani?" ke liye litres chahiye. Ek electron ka charge ( $1.6 \times 1 0^{- 19}$ C) bahut hi chota hai, isliye hum ek bucket use karte hain — coulomb — jo lagbhag 6.24 billion-billion electrons rakhti hai.

HOW to count charge — derivation from first principles

Hum ek formula chahte hain jo total charge $Q$ ko particles ki sankhya $N$ se jode.

Step 1 — Atom batao (sabse chhoti unit). Charge quantised hota hai: yeh sirf $e$ ke whole multiples mein aata hai. Tumhare paas aadhe electron ka charge nahi ho sakta.

Yeh step kyun? Yeh experimental fact hai (Millikan ka oil-drop experiment) jo hamare liye sirf count karna possible banata hai.

Step 2 — Identical pieces jodo. Agar tumhare paas $N$ particles hain, har ek $e$ charge ke saath, total charge simply sum hai: $Q = N times e + e + \dots + e = N e$

Yeh step kyun? Charge additive hota hai — do charges ek saath rakh do aur total unka sum hoga. Isliye counting = multiplication.

Step 3 — Invert karke pata karo ki 1 C mein kitne electrons hain. $N = \frac{Q}{e} = \frac{1}{1.602 \times 1 0 ^{- 19}} \approx 6.242 \times 1 0^{18}$

Yeh step kyun? Yahi exactly woh number hai jo coulomb ko define karta hai — yeh coincidence nahi hai, yeh definition hai ulta padha hua.

Figure — Define electric charge, electron, proton, and the coulomb

Worked examples

Common mistakes (Steel-manned)

Active recall

Recall Reveal karne se pehle jawab do

Charge ke do prakar kya hain? → positive aur negative
Kaunsa particle $- e$ carry karta hai? → electron
$e$ ki value? → $1.602 \times 1 0^{- 19}$ C
1 coulomb mein kitne electrons hote hain? → $6.242 \times 1 0^{18}$
Charge aur count ko jodne wala formula? → $Q = N e$

Recall Feynman: 12 saal ke bacche ko samjhao

Socho tiny invisible marbles hain. Kuch "grumpy" hain (negative — electrons) aur kuch "happy" hain (positive — protons). Grumpy aur happy marbles ek saath rehna chahte hain, lekin do grumpies ek doosre ko door dhakelte hain. Electricity sirf grumpy marbles (electrons) ka wire mein slide karna hai. Har marble thoda sa "charge" carry karta hai. Kyunki ek marble itna kam carry karta hai, hum unhe giant buckets mein count karte hain. Ek bucket-bhar ko coulomb kehte hain, aur usme lagbhag six-billion-billion marbles aate hain. Bas itna hi hai — electricity sirf in marbles ko count karna aur move karna hai!

Connections

Electric Current and the Ampere — current charge-per-second hai, $I = Q / t$ .
Voltage and Potential Difference — in charges par "push."
Conductors and Insulators — kya electrons move karne ke liye free hain.
Coulomb's Law — do charges ke beech force.
Atomic Structure — protons aur electrons kahan rehte hain.

Electric charge kya hai?

Matter ki ek fundamental property jo electric fields mein forces create karti hai; positive aur negative do prakar ki hoti hai.

Sabse chhota free negative charge kaunsa particle carry karta hai?

Electron, charge

- e = - 1.602 \times 1 0^{- 19}

Kaunsa particle

+ e

carry karta hai aur nucleus mein rehta hai?

Proton.

Elementary charge

e

kya hai?

1.602 \times 1 0^{- 19}

coulombs.

Coulomb kya hai?

Charge ki SI unit, jo lagbhag

6.242 \times 1 0^{18}

elementary charges ke barabar hai.

Total charge ko charges ki sankhya se jodne wala formula?

Q = N e

1 coulomb mein kitne electrons hote hain?

Lagbhag

6.242 \times 1 0^{18}

Atom electron kho dene par net charge kyun khota hai?

Proton ka positive charge ab poora cancel nahi hota, net

+ e

bachta hai (ek ion).

Metal wire mein current ke roop mein actually kaunsa particle move karta hai?

Electrons (negative), − se + ki taraf flow karte hain.

"Charge is quantised" ka matlab kya hai?

Charge sirf

e

ke whole-number multiples mein exist karta hai; koi fractional free charge nahi hota.