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 j (current density) changes in an exact manner, while the current I remains unaffected. The agent that is essentially responsible for it is:
1. | source of emf |
2. | the electric field produced by charges accumulated on the surface of the wire |
3. | the charges just behind a given segment of wire which push them just the right way by repulsion |
4. | the charges ahead |
Which of the following characteristics of electrons determines the current in a conductor?
1. Drift velocity alone
2. Thermal velocity alone
3. Both drift velocity and thermal velocity
4. Neither drift nor thermal velocity