196k views
4 votes
A metallic wire has a diameter of 4.12mm. When the current in the wire is 8.00A, the drift velocity is 5.40×10⁻⁵m/s. What is the resistivity of the wire?

1 Answer

4 votes

Final answer:

To find the resistivity of the wire, you can use Ohm's law in conjunction with the given information and calculate the drift velocity using the given current and cross-sectional area of the wire.

Step-by-step explanation:

To find the resistivity of the wire, we can use Ohm's law in conjunction with the given information. Ohm's law states that resistance (R) is equal to resistivity (ρ) times the length of the wire (L) divided by the cross-sectional area of the wire (A). The formula for resistance is R = ρ * (L/A). Given the diameter of the wire as 4.12mm, we can calculate the radius (r) by dividing the diameter by 2. The radius is therefore 4.12mm / 2 = 2.06mm = 2.06 * 10^-3 m.

Next, we need to calculate the cross-sectional area of the wire. The formula for the area of a circle is A = π * r^2, where π is a constant equal to approximately 3.14. Substituting the value of the radius we calculated, the area of the wire is A = 3.14 * (2.06 * 10^-3)^2. Now we have the resistivity formula as R = ρ * (L / (3.14 * (2.06 * 10^-3)^2)).

We are given the current in the wire as 8.00A and the drift velocity as 5.40 * 10^-5 m/s. These values are not directly used to calculate resistivity. However, they are useful for calculating the drift velocity (vd) using the formula I = n * q * A * vd, where I is the current, n is the number of charge carriers per unit volume, q is the charge of an electron, and A is the cross-sectional area of the wire. Rearranging the formula, we have vd = I / (n * q * A). Since we are not given the value of n, we cannot find the exact value of drift velocity.

In conclusion, we cannot determine the resistivity of the wire without knowing the number of charge carriers per unit volume. However, we can calculate the drift velocity using the given current and cross-sectional area of the wire.

User Alvis
by
7.7k points