Kirchhoff's junction rule is a statement of which fundamental physical principle?

• A. $\text{Conservation of energy}$
• B. $\text{Conservation of electric charge}$
• C. $\text{Conservation of momentum}$
• D. $\text{Ohm's law}$

Answer: (B)

Verified step by step guidance

1. Understand that Kirchhoff's junction rule deals with the currents entering and leaving a junction in an electrical circuit.
2. Recall that the rule states: The sum of currents entering a junction equals the sum of currents leaving the junction.
3. Recognize that this rule is based on the principle that electric charge cannot accumulate at the junction; it must be conserved.
4. Therefore, Kirchhoff's junction rule is a direct consequence of the conservation of electric charge.
5. Distinguish this from other principles like conservation of energy or momentum, which relate to different physical contexts.