Current Electricity

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Electric current is the rate of flow of electric charge through a conductor. I = q/t (for steady current) or I = dq/dt (for varying current). SI unit is Ampere (A). 1 ampere = 1 coulomb/1 second. Curr…

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Ohm's Law: The electric current through a conductor is directly proportional to the potential difference across it (at constant temperature and pressure). V = IR. Ohmic conductors: Metals (copper, iro…

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R = ρl/A, where R = resistance, ρ = resistivity, l = length, A = cross-sectional area. Unit of resistance: Ohm (Ω). Unit of resistivity: Ohm-meter (Ωm). Resistivity depends only on material nature, wh…

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Given: n = 6.0 × 10¹⁶ electrons/s, e = 1.6 × 10⁻¹⁹ C Solution: Total charge per second, Q = ne = 6.0 × 10¹⁶ × 1.6 × 10⁻¹⁹ = 9.6 × 10⁻³ C/s Current I = Q/t = 9.6 × 10⁻³ A = 9.6 mA…

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In series: Same current I flows through all resistors. V₁ = IR₁, V₂ = IR₂, V₃ = IR₃... Total voltage: V = V₁ + V₂ + V₃ + ... = I(R₁ + R₂ + R₃ + ...) Equivalent resistance: Rs = R₁ + R₂ + R₃ + ... Volt…

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In parallel: Same voltage V across all resistors. I₁ = V/R₁, I₂ = V/R₂, I₃ = V/R₃... Total current: I = I₁ + I₂ + I₃ + ... = V(1/R₁ + 1/R₂ + 1/R₃ + ...) 1/Rp = 1/R₁ + 1/R₂ + 1/R₃ + ... Current divisio…

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First Law (Junction Rule): Algebraic sum of currents at any junction = 0. Based on conservation of charge. ΣI = 0 Second Law (Loop Rule): Algebraic sum of potential differences in any closed loop = 0.

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Wheatstone Bridge: Used to measure unknown resistance accurately. Four resistances P, Q, R, S connected in diamond shape with galvanometer between opposite corners. Balance condition: P/Q = R/S (or PS…