Circuit Analysis (original) (raw)
Electric Current If dq coulombs of charge flow across any cross-section of a conductor in time dt, then the magnitude of the current I flowing through it is given by : dq I dt Thus an electric current may be defined as the rate of flow of electric charges across any cross-section of a conductor. The S.I. unit of current is ampere and is denoted as A. One ampere current is said to flow through a conductor when a charge of 1 coulomb passes through any crossection in 1 second. 1 A = 1 C/ 1 s 1 mA = 10-3 A, 1 µA = 10-6 A In metals, the carriers of electric current are negatively charged electrons. As a matter of convention, the direction of electric current is taken as the direction of flow of positive charges. In electrolytes, the carriers of electric current are ions. The amount of charge flowing through a crossection of a conductor from t = t i to t = t f is given by : f i t t q I dt Specific Resistance or Resistivity :