plz help me with the sign conventions regarding the kirchoffs laws.when we are given a circuit with many loops containing many cells.how can we distribute the direction of current in each of the different branches of it.

Asked by vishnuraj | 25th May, 2012, 06:53: AM

Expert Answer:

Sign Convention in Applying Kirchhoff's Rules

The emf of a cell is positive when one moves in the direction of increasing potential (i.e., negative pole to positive pole) through the cell and is negative when one moves from positive to negative.

 

 

The product of resistance and current, i.e., the IR term, in any arm of the circuit is taken negative if one moves in a closed path, in the same direction of the assumed current; and positive if in the opposite direction.

 

 

Steps to solve circuits by Kirchhoff's laws:

  • Assume unknown currents in a given circuit and show their directions by arrows.
  • Choose any closed loop and find the algebraic sum of voltage drops plus the algebraic sum of the emfs in that closed loop and equate it to zero.
  • Write equations for as many closed loops as the number of unknown quantities. Solve the equations to find the unknown quantities.
  • If the value of assumed current is negative, it means that the actual direction of the current is opposite to that of the assumed direction.

Answered by  | 25th May, 2012, 06:59: AM

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