Wil S. answered • 06/28/21
Electrical Engineer
a) Use KVL to solve for V4
-V3 + V4 - V5 = 0
-8 + V4 - 3 = 0
V4 = 8 + 3
V4 = 11 V
Use KVL to solve for V6
V5 + V7 + V6 = 0
3 + 6 + V6 = 0
V6 = -9 V
Use KVL to solve for V1
-V1 - V2 +V3 -V6 = 0
-V1 - 12 + 8 - (-9) = 0
V1 = -12 + 8 + 9
V1 = 5 V
b)
Current through element 2
Elements 1 and 2 are in series, so the current through them is equal making the current through element 2 be 5 A.
Current through 3
Use KCL around the node connecting elements 2, 3 and 4. We will assume the current flowing through element 3 is entering the node.
5 - 4 + x = 0
x = -1 A
Since x is negative, x we were wrong with our assumption of the current flow direction. Therefore, the current going through is 2 A flowing from the positive terminal to the negative terminal, which is leaving the node.
Current through 5
Use KCL around the node connecting elements 3, 5 and 6. We will assume the current flowing through element 5 is entering the node.
1 + x - 2 = 0
x = 1 A
Since x is positive, we were correct with our assumption of the current flow direction. Therefore, the current going through element 5 is 1 A going from the negative terminal, to the positive terminal, which is entering the node.
Current through 7
Use KCL around the node connecting elements 1, 6 and 7. We will assume the current flowing through element 7 is entering the node.
-5 + 2 + x = 0
x = 3
Since x is positive, we were correct with our assumption of the current flow direction. Therefore, the current going through element 7 is 3 A going from the positive terminal, to the negative terminal, which is entering the node.
c) If a positive current is leaving the positive terminal of an element, then the element is supplying power. Otherwise, the element is receiving power. Therefore, elements 1, 2, 5, and 6 are suppliers of power and elements 3, 4, and 7 are receivers of power.
