Current Electricity – Class 12 Physics Notes
๐ Chapter 3: Current Electricity – Class 12 Physics Notes Label: Physics, Class 12, Current Electricity --- ๐น Introduction Deals with the flow of electric charge through conductors, mainly metals. Covers Ohm’s law, resistivity, combination of resistors, emf, Kirchhoff’s laws, and cells. --- ⚡ Electric Current Electric current (I) is the rate of flow of electric charge: I = Q / t Unit: Ampere (A) Direction: From positive to negative terminal (conventional direction) --- ๐ Electric Current in Conductors Carried by free electrons in metals Flow due to potential difference (voltage) --- ⚙️ Drift Velocity Average velocity of electrons due to electric field vd = eEฯ / m Where: e = electron charge E = electric field ฯ = relaxation time m = mass of electron --- ๐ Current and Drift Velocity Relation I = neAvd Where: n = number of electrons per unit volume A = cross-sectional area vโ = drift velocity --- ๐งช Ohm’s Law Voltage is directly proportional to current: V = IR Where: R = resista...