Item 5:

Within a simple electric circuit a constant current is flowing through a resistor. For reasons of simplicity the diameters of the conductors and the resistor are given to be the same.

Since there is practically no potential difference along the conductors but mainly across the resistors, it can be concluded that the electric field within the resistor will be much larger than within the conductors.

Question:

Where does this extra field within the resistors come from?

Which of the following answers do you think is correct or makes sense to you?

1) The strong field inside of the resistor is produced by the battery which drives the current.
2) There should be extra electrons at one end and positive charges at the
other end of the resistor, but I am not sure.
3) There are extra electrons at one end and positive charges at the other end of the resistor.
4) The energy of the drifting electrons, forming the electric current, is different at both ends of the resistor.

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