Question

Kirchhoff's first law, i.e. $\sum i =0$ at a junction, deals with the conservation of

• A. momentum
• B. angular momentum
• C. charge
• D. energy

Answer 1

The Correct Option is C

Kirchhoff's first law, also known as the Junction Rule or the Current Law, pertains to the conservation of charge. This law is based on the principle that electrical charge is conserved within a closed system. Let's understand this in detail:

1. Understanding Kirchhoff's First Law: Kirchhoff's first law states that the total current entering a junction must equal the total current leaving the junction. Mathematically, this is represented as $\sum i = 0$, where $i$ represents the current.

2. Conservation of Charge: The law directly follows from the principle of conservation of charge. This principle states that charge can neither be created nor destroyed. At any junction in an electric circuit, the charge that flows into the junction flows out, ensuring no charge accumulation at the junction.

3. Eliminating Other Options:

   • Momentum: This relates to the mass and velocity of a body, not relevant to electrical circuit laws.
   • Angular Momentum: This involves rotational motion, which is unrelated to electrical circuits.
   • Energy: Although energy conservation is crucial in circuits, Kirchhoff's first law specifically addresses current flows, implying charge conservation.

4. Conclusion: Given the concepts discussed, the correct answer is conservation of charge. Therefore, Kirchhoff's first law, $\sum i = 0$ at a junction, deals with the conservation of charge.