Question

Electrons in an electric circuit pass through a resistor. The wire on either side of the resistor has the same diameter.(a) How does the drift speed of the electrons before entering the resistor compare to the speed after leaving the resistor? (b) How does the potential energy for an electron before entering the resistor compare to the potential energy after leaving the resistor? Explain your reasoning.

Short answer

(a) The velocity is similar before entering and leaving.

(b) The potential energy is high during entering as compared to leaving.

Step-by-step solution

Definition of drift speed

The mean velocity obtained by charged electrons in a material owing to an electric field is known as drift velocity.

Determine the reasoning

(a) The drift velocity relation is

${\stackrel{\rightharpoonup }{\mathrm{v}}}_{\mathrm{d}}=\frac{\stackrel{\rightharpoonup }{\mathrm{J}}}{\mathrm{n}\left|\mathrm{q}\right|}$

Here, ${\stackrel{\rightharpoonup }{\mathrm{v}}}_{\mathrm{d}}$is the drift velocity, $\stackrel{\rightharpoonup }{\mathrm{J}}$is the current density, n is the number of electrons, and q is the charge of electron.

This relation all parameters are not changed in any condition.

Hence, the velocity is similar before entering and leaving.

(b) The two relations are

$$\begin{gathered} \mathrm{U}=\mathrm{qV} \\ =\mathrm{eV} \end{gathered}$$

Here U, e, V is potential energy, the charge of an electron, and potential difference respectively. The potential difference is high during entering than leaving the resistor.

Hence, the potential energy is high during entering as compared to leaving.