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Current Electricity — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity1 Mark
MCQ
Kirchhoff ’s junction rule is a reflection of:
  • A
    Conservation of current density vector.
  • B
    Conservation of charge.
  • C
    The fact that the momentum with which a charged particle approaches a junction is unchanged (as a vector) as the charged particle leaves the junction.
  • D
    The fact that there is no accumulation of charges at a junction.
✓

Answer

  1. Conservation of charge.
  1. The fact that there is no accumulation of charges at a junction.

Solution:

Key concept: Junction rule: At any junction, the sum of the currents entering the junction is equal to the sum of currents leaving the junction.

Or
Algebraic sum of the currents flowing towards any point in an electric network is zero, i.e., charges are conserved in an electric network.

The proof of this rule follows from the fact that when currents are steady, there is no accumulation of charges at any junction or at any point in a line.

Thus, the total current flowing in, (which is the rate at which charge flows into the junction), must equal the total current flowing out.

Kirchhoffs junction rule is also known as Kirchhoff’s current law.

So, Kirchhoffs junction rule is the reflection of conservation of charge

Important point: Sign convention of current from a junction: We are taking outgoing current from a junction as negative. And we are taking incoming current towards a junction as positive.

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