Friday, December 25, 2015

Electrical Circuit Theorems for Circuit Analysis

Electrical Circuit Theorems:

To solve problems in electrical networks, there are number circuit theorems have been developed like
(1) Kirchhoff's laws
(2) Superposition theorem
(3) Thevenin theorem
(4) Norton Theorem
(5) The maximum power transfer theorem

In this post we have listed all these theorems. We believe that this post will serve as a ready reference for you.

Kirchhoff's laws:
(a) Current Law:
 At any junction in an electric circuit the total current flowing towards that junction is equal to the total current flowing away from the junction, i.e. I =0

(b) Voltage Law:
 In any closed loop in a network, the algebraic sum of the voltage drops (i.e.products of current and resistance) taken around the loop is equal to the resultant e.m.f. acting in that loop.

Superposition Theorem:
In any network made up of linear resistances and containing more than one source of EMF, the resultant current flowing in any branch is the algebraic sum of the currents that would flow in that branch if each source was considered separately, all other sources being replaced at that time by their respective internal resistances.

Thevenin Theorem:
The current in any branch of a network is that which would result if an EMF. equal to the potential differential across a break made in the branch, were introduced into the branch, all other EMFs being removed and represented by the internal resistances of the sources.

Norton Theorem:
The current that flows in any branch of a network is the same as that which would flow in the branch if it were connected across a source of electrical energy, the short-circuit current of which is equal to the current that would flow in a short-circuit across the branch, and the internal resistance of which is equal to the resistance which appears across the open-circuited branch terminals.

The Maximum Power Transfer Theorem:
The power transferred from a supply source to a load is at its maximum when the resistance of the load is equal to the internal resistance of the source

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