Question

Consider a current carrying wire (current I) in the shape of a circle. Note that as the current progresses along the wire, the direction of $\overrightarrow { \mathrm { J } }$ (current density) changes in an exact manner, while the current I remains unaffected. The agent that the essentially responsible for it is

• A. Source of emf.
• B. Electric field produced by charges accumulated on the surface of wire.
• C. The charges just behind a given segment of wire which push them just right way by repulsion
• D. The charges ahead.

Answer 1

Answer: (B)

Electric field produced by charges accumulated on the surface of wire.

Answer 2

: The direction of current density is the direction of flow of positive charge in the circuit which is possible due to electric field produced by charges accumulated on the surface of wire.