what are sign conventions of kirchoffs rule give alll in order to understand concept properly

Asked by Farooq Ahmad Shah | 14th Jun, 2015, 09:27: PM

Expert Answer:

For analysing circuits Kirchoff's law are used.
First Law: The algebric sum of the currents meeting at a junction in a circuit is zero.
 
begin mathsize 12px style The space current space flowing space towards space the space jucntion space is space taken space as space positive space and space the space curent space leaving space the space junction space is space taken space as space negative. From space the space figure comma space straight I subscript 1 space and space straight I subscript 2 space are space flowing space towards space the space junction space and space are space taken space as space positve. space The space current space straight I subscript 3 space and space straight I subscript 4 space are space leaving space juntion space and space are space taken space as space negative. rightwards double arrow space straight I subscript 1 space space plus space straight I subscript 2 space minus space straight I subscript 3 space minus space straight I subscript 4 space equals space 0 end style
 
Second Law: In any closed loop of an electric circuit caontaining cells and resistors, the algebric sum of changes in potential is zero
 
        begin mathsize 12px style In space straight a space closed space loop space ΔV space is space the space change space in space potential space across space all space the space resistance space and space cells. As space Shown space in space fig comma space ΔV space equals space IR space is space taken space as space negative space when space move space in space the space direction space of space current space and space ΔV space is space taken space positive space when space move space opposite space to space the space direction space of space current. end style
      
 
As shown in fig.,
begin mathsize 12px style The space emf space apostrophe straight E apostrophe space is space taken space as space positive space when space moves space from space the space negative space terminal space to space the space positive space terminal space straight i. straight e. space ΔV space equals space plus straight E space and space taken space as space negative space when space it space move space from space the space positive space terminal space to space negative space terminal space straight i. straight e. space ΔV space equals space minus straight E end style
 
From the sign convention we can solve the numerical.
Suppose we have circuit, 
 
This circuit can be solved in accordance of sign convention is given as,
 
From above circuit, we get (i), (ii), and (iii) equations.
 

Answered by Priyanka Kumbhar | 15th Jun, 2015, 08:47: AM