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Question : 16
Total: 29
Use Kirchhoff's rules to determine the value of the current I 1
Solution:
The given circuit:M KCL
I 3 = I 1 + I 2
In loop MPQN, applying KVL,
20 I 3 + 30 I 1 = 20
Or, 20 ( I 1 + I 2 ) + 30 I 1 = 20
Or, 50 I 1 + 20 I 2 = 20
Or, 5 I 1 + 2 I 2 = 2
In loop MSTN, applying KVL,
− 20 I 2 − 20 I 3 = − 20 − 80 = − 100
Or, − 20 I 2 − 20 ( I 1 + I 2 ) = − 100
Or, − 20 I 1 − 40 I 2 = − 100
Or, − I 1 − 2 I 2 = − 5
Solving equations (i) and (ii)
I 1 = −
A
At node
In loop MPQN, applying KVL,
In loop MSTN, applying KVL,
Solving equations (i) and (ii)
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