Kirchoff's current law question

Click For Summary
SUMMARY

The discussion centers on the application of Kirchoff's Current Law (KCL) in the context of a band pass filter circuit involving a capacitor and resistor in parallel. The user initially believes that the current through the capacitor (Ic) should equal the incoming current (I) minus the current through the resistor (Ir), expressed as Ic = I - Ir. However, the derivation presented in the discussion states that Ic = Ir - I, highlighting the importance of current direction conventions. The confusion arises from the definitions of current flow, specifically the passive sign convention versus the conventional current flow direction.

PREREQUISITES
  • Understanding of Kirchoff's Current Law (KCL)
  • Basic knowledge of circuit components: capacitors and resistors
  • Familiarity with band pass filter design principles
  • Concept of passive sign convention in electrical engineering
NEXT STEPS
  • Review the principles of Kirchoff's Current Law in various circuit configurations
  • Study the derivation and application of band pass filter circuits
  • Learn about passive sign convention and its implications in circuit analysis
  • Explore the differences between conventional current flow and electron flow
USEFUL FOR

Electrical engineers, students studying circuit theory, and anyone involved in designing or analyzing filter circuits will benefit from this discussion.

bitrex
Messages
190
Reaction score
0
I'm looking at the derivation of a band pass filter circuit, and part of the circuit is a capacitor and resistor in parallel from the non-inverting input to the output. My thinking is that the current through the capacitor is going to be the current coming in (since the inverting input draws no current) minus the current going through the resistor, or Ic = I - Ir. Nope, the derivation has it the other way, Ic = Ir - I. I can't figure out why this is.
 
Engineering news on Phys.org
depends on the standardization of current. If current is defined as direction holes travel in, than it follows passive sign convention whereas, current is usually defined as direction opposite of electron flow. I see your point. Ic + Ir = I so
Ic = I - Ir...
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
Replies
3
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 14 ·
Replies
14
Views
2K
  • · Replies 6 ·
Replies
6
Views
8K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 21 ·
Replies
21
Views
3K
Replies
15
Views
3K
  • · Replies 15 ·
Replies
15
Views
2K