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A student writes $I_1+I_2+I_3+I_4+I_5+I_6=0$ for the junction in the figure without assigning signs. Why is this incorrect? 
ABecause Kirchhoff's Current Law applies only to two-branch junctions
BBecause currents entering and leaving must be given opposite signs in an algebraic sum
CBecause current cannot be added at a junction
DBecause only outgoing currents should be written in the equation
Answer & Solution
Correct answer: B. Because currents entering and leaving must be given opposite signs in an algebraic sum
KCL is an algebraic statement: entering currents and leaving currents must carry opposite signs. Writing all currents with the same sign ignores direction. The correct idea is either entering sum equals leaving sum, or the signed sum of all currents is zero.