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on April 27, 2020
KIRCHHOFF’S VOLTAGE LAW
Kirchhoff’s Voltage law
The algebraic sum of the potential difference in any closed loop is equal to zero. The total sum of all E,m,f in a closed loop is equal to the total sum of the voltage (IR) drops in the loop.
From the diagram( fig 1) above
Where
are the internal resistances of the cells
Positive and Negative E.m.f with Kirchhoff law
See figure 2 above to know when to use -E or +E
Positive and Negative IR with Kirchhoff law
See figure 3 above to know when to use -IR or +IR
Example
Calculate the current across the 3Ω resistor in fig 4 above. What is the voltage across ab ?
Solution
The two 10Ω resistors are parallel 10‖10 =5Ω
Total voltage = 12-4=8v
8=3I+2I+4I+5I
8 =14I
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kirchhoffs voltage law
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