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Hello everyone, I am understanding the concept of mesh analysis and super meshes. In the Practice problem below, I am presented with a dependent current source and it lies between mesh 2 and mesh 3. Therefore, a super mesh will be utilized. However, on my third equation circled in red, I keep getting the signs wrong. How do I get them right?

  • 1
    \$\begingroup\$ No, don't use a super-mesh. I hate them. And they aren't ever needed. Do you really have to use one? \$\endgroup\$
    – jonk
    Commented Sep 22, 2021 at 4:39
  • \$\begingroup\$ Yes I have to understand this concept as it is part of the lecture \$\endgroup\$ Commented Sep 22, 2021 at 5:17
  • \$\begingroup\$ Just look at the direction in which the net current flows. Since the net current flows from left to right, which says that i3 is greater than i2. Hence, you should subtract i2 from i3. i2 is opposite in direction to i3. \$\endgroup\$ Commented Sep 22, 2021 at 5:20
  • \$\begingroup\$ supermesh is not any concept. It is just some 'trick' derived from KVL, KVL is the CONCEPT. \$\endgroup\$
    – Mitu Raj
    Commented Sep 22, 2021 at 5:33
  • \$\begingroup\$ @Jonathan_the_seagull I have subtracted i2 from i3 but according to the answer from the book it is i3 - i2 \$\endgroup\$ Commented Sep 22, 2021 at 5:48

1 Answer 1


The direction of the net current as indicated by the current controlled current source is in the direction of i3. i2 has a direction opposite to i3 in the middle arm. Since the direction of the net current and the direction of i3 is same, we can say that i3-i2 is equal to 15i1(which is the net current).


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