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Answers
Answer:
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Explanation:
Kirchhoff’s Second law: Loop law
Loop law is also known as Kirchhoff’s Second Law.
It states that in a closed loop,algebraic sum of Emfsis equal to the algebraic sum of product of resistances and respective currents flowing through them.
Consider a simple circuit havingEmfs = E1 and E2; R1 and R2 =resistances; current =I1 and I2.
Then according to this law : E1+E2=I1R1+ I2R2
For example:-
Consider given figure,let Emfs be E1 and E2 internal resistances be R1, R2 and R3.
Steps to use Kirchhoff’s law:-
Choose the loop to apply Kirchhoff’s law.
Assume any direction.
Emf is +ive if assumed direction leaving +ive terminal of battery.
IR is +ive if the current in the assumed direction.
Consider closed loop ABCDFA, using the assumptions;
E2=+R2I3 +R3I2 ;where I3=current flowing through R3
Closed loop FCDEF, +E1= +I1R1 + I3R2
Closed loop ABDEA, -E1 + E2 = -I1R1 +I2R3
If the direction of current is taken opposite then
Closed loop ABCDFA ;- -E2=-R2I3-R3I2
FCDEF; -E1= -I1R1 - I3R2
ABDEA; +E1 - E2 = +I1R1 -I2R3
Kirchhoff's voltage law (2nd Law) states that the sum of all voltages around any closed loop in a circuit must equal zero. This is a consequence of charge conservation and also conservation of energy.
As charge carriers flowing through a circuit pass though a component, they either gain or lose electrical energy, depending upon the component (cell or resistor, for example). This is due to the fact that work is done on them by the electric forces inside the circuit components. The negative of the work done by these electric forces on a unit of charge which passes through a component is called the potential difference, or voltage, across the component. In most circuits, the work done by the electric forces around any closed loop in the circuit must be zero. This means that the sum of all potential differences across the component involved in the loop must be zero. This explains why connecting both ends of a voltmeter to the same point in a circuit gives a zero reading, as expected.
Kirchhoff's voltage law can be generalised to any loop containing any number of components. A more formal way of writing