1. Electric Charge
Electric charge matter ki intrinsic property hai jiske karan wo electrostatic aur magnetic effects produce tatha experience karta hai.
- Types of Charges: Positive (+ve) and Negative (-ve).
- SI Unit: Coulomb (C)
- Dimensional Formula: [A T]
Basic Properties of Electric Charge
- Quantization of Charge: Kisi bhi body par total charge hamesha elementary charge (e = 1.6 × 10-19 C) ka integral multiple hota hai.
q = ± ne (n = 1, 2, 3...) - Conservation of Charge: Kisi isolated system ka total charge hamesha constant (conserved) rehta hai. Charge ko na to banaya ja sakta hai aur na hi nasht kiya ja sakta hai.
- Additive Nature: Real numbers ki tarah kisi system ke sabhi charges ka algebraic sum total charge banata hai:
Q = q₁ + q₂ + q₃ + ...
2. Coulomb’s Law
Do stationary point charges ke beech lagne wala electrostatic force unke charges ke product ke directly proportional aur unke beech ki doori (distance) ke square ke inversely proportional hota hai.
F = [1 / (4πε₀)] × [|q₁ q₂| / r²]
Yahan 1 / (4πε₀) = 9 × 10⁹ N·m²/C² aur ε₀ = 8.854 × 10⁻¹² C²N⁻¹m⁻²
3. Electric Field & Field Intensity
Kisi charge ke charo taraf ka wo region jisme koi doosra test charge ek force experience karta hai, use Electric Field kehte hain.
- Electric Field Intensity (E):
E = F / q₀ - SI Unit: N/C ya V/m
- Point Charge ke karan Field:
E = [1 / (4πε₀)] × (q / r²)
4. Electric Dipole & Dipole Moment
Jab do equal aur opposite charges bahut small distance (2a) par rakhe hote hain, toh is arrangement ko Electric Dipole kehte hain.
- Dipole Moment (p):
p = q × 2a(Direction: Negative se Positive charge ki taraf). - SI Unit: Coulomb-meter (C·m)
Important Board Derivations:
1. Axial Line (End-on position):
Short Dipole ke liye: E_axial = [1 / (4πε₀)] × (2p / r³)
2. Equatorial Line (Broadside-on position):
Short Dipole ke liye: E_equatorial = [1 / (4πε₀)] × (p / r³)
Relation: E_axial = 2 × E_equatorial
5. Electric Flux & Gauss’s Law
Electric Flux (Φ): Kisi surface area se perpendicularly pass hone wali total electric field lines ka measure hai.
Φ = E · A = E A cosθ (SI Unit: N·m²/C ya V·m)
Gauss's Theorem
Kisi closed surface se guzarne wala total electric flux (Φ) uske andar enclosed total charge ka 1 / ε₀ guna hota hai.
Φ = ∮ E · dA = q_enclosed / ε₀
Gauss's Law Applications:
- Infinite Long Straight Wire:
E = λ / (2πε₀r) - Infinite Thin Plane Sheet:
E = σ / (2ε₀)