Kirchhoff’s First Law

Kirchhoff’s First Law states that the total current entering a junction is equal to the total current leaving the junction. OR The algebraic sum of currents at a junction is zero.

Kirchoff current rule

Referring to the diagram above, the current entering any junction is equal to the current leaving that junction. Hence, i1 + i4 = i2 + i3

Kirchhoff’s first law is a statement of the conservation of charges.

  • Whatever current enters a given junction in a circuit must leave that junction since charge cannot be created or destroyed at a junction.
  • Charge cannot escape from the wire but has to flow around the circuit.

Video of the Kirchhoff’s First Law. The ‘i’ in the video is current. (Not a complex number)

Back To DC Circuits (A Level Physics)

Back To A Level Physics Topic List

Mini Physics

Administrator of Mini Physics. If you spot any errors or want to suggest improvements, please contact us. If you like the content in this site, please recommend this site to your friends!

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.