MCQ
$A$ current passes through a wire of nonuniform cross section. Which of the following quantities are independent of the cross-section?
- Athe charge crossing in a given time interval.
- Bdrift speed
- Cfree-electron density.
- ✓Both $(A)$ and $(C)$
✓
Answer
Correct option: D.
Both $(A)$ and $(C)$
d
As the current passes, the value of current at any point in the circuit remains the same. Therefore the charge crossing in any given interval is same and does not change with the cross section of the wire
As the current passes, the value of current at any point in the circuit remains the same. Therefore the charge crossing in any given interval is same and does not change with the cross section of the wire
$I=J A$
As $A -cross$ section of wire changes, $J -current$ density changes and $I$ current remains same.
The free electron density is a property of the material and doesnot change when current passes.
As the cross section changes, current density changes and hence the drift velocity changes.
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