After reading many question and answers on stack, i got totally confused about how does resistor affect drift velocity.
Consider a simple circuit, a battery and a resistor, connected to each other with wire ( wire with area $A$ and resistivity $\rho_w$ (very small), resistor with area $A$ and resistivity $\rho_r$ ; $\rho_w \ll \rho_r$). From the formula $v=\frac{I}{enA}$, we can conclude that overall drift velocity in circuit decreases by using a larger resistor (as it reduces the current).
Having constant current density $J$, electrical field in wire is $E_w = J \rho_w$ and resistor $E_r = J \rho_r$. As $\rho_w < \rho_r$, it says that electrical inside resistor is stronger than in wire. So the greater the electrical field, the more force on electrons and thus an increase in their speed (drift velocity). ( The increase in drift velocity can be concluded in another way : For both wire and resistor, all parameters in formula $v=\frac{I}{enA}$ are equal except $n$, charge carrier density. So drift velocity in resistor with less charge carrier density must be larger. )
Now some questions :
- It is correct to say that having a resistor in a circuit, slows down the overall drift velocity comparing to another circuit with a lower resistor, but inside a circuit itself, drift speed in resistor is more than in wire ?
- It is correct to say that in any element with nonzero resistor, as electrons move in opposite direction of electrical field, they lose electrical potential energy and it's get converted to kinetic energy and heat?
- Considering the simple circuit, if wires have zero resistance, does electrons flow through ? (Noting that there is no potential difference, so electrons have no electrical potential energy to convert to kinetic energy and start moving toward other terminal of battery)
- Does voltage drop mean that electrons have lost some electrical potential energy or it means that there are more electrons on one side of the resistor compared to the other side?