32a is redrawn in fig 32b where we now add i1 i2 and

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: , the circuit in Fig. 3.2(a) is redrawn in Fig. 3.2(b), where we now add i1 , i2 , and i3 as the currents through resistors R1 , R2 , and R3 , respectively. At node 1, applying KCL gives I1 = I2 + i1 + i2 77 The number of nonreference nodes is equal to the number of independent equations that we will derive. (a) Figure 3.1 Common symbols for indicating a reference node. I2 (3.1) At node 2, I2 + i2 = i3 (c) (b) R2 1 2 (3.2) We now apply Ohm’s law to express the unknown currents i1 , i2 , and i3 in terms of node voltages. The key idea to bear in mind is that, since resistance is a passive element, by the passive sign convention, current must always flow from a higher potential to a lower potential. I1 + v1 − + v2 − R1 R3 0 (a) Current flows from a higher potential to a lower potential in a resistor. I2 We can express this principle as i= vhigher − vlower R v1 i2 R2 i2 v2 i1 (3.3) I1 i3 R1 R3 Note that this principle is in agreement with the way we defined resistance in Chapter 2 (see...
View Full Document

Ask a homework question - tutors are online