9.2 Model of Conduction in Metals

In the example, the drift velocity was calculated for a 2.053-mm diameter (12-gauge) copper wire carrying a 20-amp current. Would the drift velocity change for a 1.628-mm diameter (14-gauge) wire carrying the same 20-amp current?

The current density is proportional to the current and inversely proportional to the area. If the current density in a conducting wire increases, what would happen to the drift velocity of the charges in the wire?

It was stated that the motion of an electron appears nearly random when an electrical field is applied to the conductor. What makes the motion nearly random and differentiates it from the random motion of molecules in a gas?

An incandescent light bulb is partially evacuated. Why do you suppose that is?

The current of an electron beam has a measured current of $I = 50.00 \mu \text{A}$ with a radius of 1.00 mm. What is the magnitude of the current density of the beam?

Consider a wire of a circular cross-section with a radius of $R = 3.00 \text{mm}$. The magnitude of the current density is modeled as $J = c r^{2} = 5.00 \times 10^{6} \frac{\text{A}}{\text{m}^{4}} r^{2}$. What is the current through the inner section of the wire from the center to $r = 0.5 R$?

The current supplied to an air conditioner unit is 4.00 amps. The air conditioner is wired using a 10-gauge (diameter 2.588 mm) wire. The charge density is $n = 8.48 \times 10^{28} \frac{\text{electrons}}{\text{m}^{3}}$. Find the magnitude of (a) current density and (b) the drift velocity.