Alternating Current Class 12 Physics Notes – Formulas & Quick Revision

AC chapter mein RMS values, LCR circuit, resonance aur transformer aate hain — phasors se khelne ka chapter. Yahan aapko is chapter ke sabse important formulas aur quick revision points free milte hain — NCERT/CBSE syllabus ke hisaab se, boards aur JEE/NEET dono ke liye.

Important Formulas & Concepts — Alternating Current

• I_rms = I₀/√2; V_rms = V₀/√2
• X_L = ωL; X_C = 1/ωC
• Impedance: Z = √[R² + (X_L − X_C)²]
• tanφ = (X_L − X_C)/R
• Resonance: X_L = X_C; f₀ = 1/2π√(LC); Z = R (minimum)
• Power: P = V_rms·I_rms·cosφ
• Q-factor = ω₀L/R
• Transformer: V₂/V₁ = N₂/N₁ = I₁/I₂ (ideal)

Quick Revision Points

• Pure L mein current 90° lag, pure C mein 90° lead (CIVIL yaad rakho)
• Resonance par current maximum, power factor 1
• Choke coil power kam waste karta hai (ideal mein zero)
• Step-up: N₂ > N₁, V badhta hai par I ghatta hai
• Wattless current: pure L ya C mein average power zero

FAQ

Phasor diagrams zaroori hain?

Haan — LCR ke derivations phasor se hi aate hain. PDF mein ready phasor maps hain.

Resonance ke numericals?

f₀ formula + Q-factor — PDF ke solved patterns se 2 minute ka kaam.

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