A student writes for a junction, 'the algebraic sum of currents at a node is zero.' This is equivalent to Kirchhoff's Current Law provided
AAll currents are treated as positive regardless of direction
BCurrents entering and leaving are assigned opposite signs
COnly incoming currents are included
DThe node has exactly three branches
Answer & Solution
Correct answer: B. Currents entering and leaving are assigned opposite signs
The statement 'algebraic sum is zero' works only when a sign convention is used, such as currents entering positive and leaving negative, or vice versa. Then KCL becomes $\sum I=0$, equivalent to incoming current equals outgoing current.
Related questions
For a battery of emf ε and internal resistance r driving current I through external resistA galvanometer of resistance G is converted into a voltmeter reading full-scale voltage V A galvanometer of resistance G shows full-scale deflection at current I_g. To convert it iThe relation between current density j, drift velocity v_d, number density n and charge e A wire has a resistance R. It is stretched uniformly so that its length becomes 2L. The neKirchhoff current law at a junction is a statement ofTwo cells of emf ε and internal resistance r each are connected in parallel. The equivalenA potentiometer of length L is used to compare emfs. If the balance lengths for cells of e