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Current through an area of cross-section is treated as a scalar quantity in this chapter even though it is shown with an arrow. The justification is that
Acurrent always flows in a single direction
Bcurrents do not obey the law of vector addition
Ccurrent density is itself a scalar
Dcurrent has no defined direction in a wire
Answer & Solution
Correct answer: B. currents do not obey the law of vector addition
1. A vector quantity must combine by the parallelogram (vector) law of addition.
2. Currents meeting at a junction simply add algebraically, not as vectors.
3. Hence current fails the vector-addition test and is treated as a scalar.
4. Current density j is a vector (so C is wrong), and current does have a direction (D wrong).
_Source: NCERT Class 12 Physics Ch 3 "Current Electricity", p.23_
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