the direction of flow of positive charge, whereas the direction of flow of electrons gives the direction of electronic current which is opposite to that of conventional current. ![]() The arrow head marked in circuit represents the direction of conventional current i.e. The direction of current therefore is taken as opposite to the flow of electrons.Ĭharge= Area under the graph = ½ × t 0 × I 0įor Simple circuit or single wire, we have:įor complex circuit with more than one wire we can determine current by the means of Kirchhoff’s two lawsįirst Law: This law is based on the principle of conservation of charge and states that in an electrical circuit (or network of wires) the algebraic sum of currents meeting at a point is zero. In conduction although the current is only due to electrons, the current was earlier assumed to be due to positive charges flowing from the positive of the battery to the negative. The direction of current is taken as the direction in which positive charges move. In metallic conductors the current is due to the motion electrons whereas in electrolytes and ionized gases, both electrons and positive ions move in opposite direction. The S.I unit of current is called ampere (A) (coulomb/second). If a charge Q flows through the circuit for time t, then If rate of flow of charge is not constant then the current at any instant is given by the differential limit: I = dQ/dt. ![]() ![]() The rate of flow of charge through a cross section of some region of a metallic wire (or an electrolyte) is called the current through that region. If the electric power and the total resistance are known, then the current can be determined by using the following formula:
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