Current Electricity Class 12 Physics Notes – Formulas & Quick Revision

Current Electricity numericals ka powerhouse hai — Ohm law, Kirchhoff laws, Wheatstone bridge aur meter bridge sab yahan. 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 — Current Electricity

• I = Q/t = nAev_d
• Ohm law: V = IR; R = ρL/A
• Resistivity: ρ = m/(ne²τ)
• Series: R = R₁+R₂; Parallel: 1/R = 1/R₁+1/R₂
• Kirchhoff: ΣI = 0 (junction), ΣV = 0 (loop)
• Wheatstone balance: P/Q = R/S
• Cells: series I = nE/(R+nr); parallel I = E/(R+r/n)
• Power P = VI = I²R = V²/R; H = I²Rt

Quick Revision Points

• Drift velocity bahut chhoti hoti hai (~mm/s)
• Balanced Wheatstone mein galvanometer arm hata do
• Internal resistance: V = E − Ir
• Meter bridge: R = S·l/(100−l)
• Max power transfer jab R = r

FAQ

Kirchhoff ke sign conventions?

PDF mein loop-rule ka visual sign map hai — direction fix karo, signs khud aa jayenge.

Ye chapter kitne marks ka hai?

Boards mein 7-8 marks tak — numericals + derivations dono.

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