Kirchoff’s Laws  

 Kirchoff’s Laws are based on two very basic principles of energy conservation and charge conservation in a circuit. While the Loop Rule is based on conservation of energy, the Junction Rule is based on the conservation of charge. The rules have been described below. 
The Loop Rule: The algebraic sum of the changes in potential encountered in a complete traversal of any loop in a circuit must be zero. 
The Junction Rule: The sum of the currents entering any junction must be equal to the sum of currents leaving that junction. 
While applying the Kirchoff’s laws the following sign convention should be kept in mind: 

There is a drop in potential in the direction of flow of the current through a conductor and vice versa (current always flows from a point of higher potential to a point of lower potential). (Fig.1)

The change in potential in the direction from the negative terminal of a battery to the positive terminal of a battery is always positive and is equal to the magnitude of the emf across it.


Figure 1 Sign conventions followed in circuitry


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Quiz
Figure 2 


In Figure 2 which of the following equations is true?


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