Question

Two cylindrical bars, each with diameter of 2.30 cm, are welded together end to end. One of the original bars is copper and is 0.350 m long. The other bar is iron and is 0.175 m long. What is the resistance between the ends of the welded bar at 20�C?

Answer 1

To find the resistance between the ends of the welded bar, calculate the resistance of each individual bar using the resistance formula and add them together.

Step-by-step explanation:

To find the resistance between the ends of the welded bar, we need to calculate the resistance of each individual bar and add them together. The resistance of a cylindrical bar can be calculated using the formula:

R = (ρ × L) / A

where R is the resistance, ρ is the resistivity of the material, L is the length of the bar, and A is the cross-sectional area of the bar.

First, we calculate the resistance of the copper bar:

Rcopper = (ρcopper × Lcopper) / Acopper

Substituting the values, we get:

Rcopper = (1.68 × 10-8 Ω·m × 0.35 m) / ((π × (0.023 cm / 2)2) m2)

Similarly, we calculate the resistance of the iron bar:

Riron = (ρiron × Liron) / Airon

Substituting the values, we get:

Riron = (9.71 × 10-8 Ω·m × 0.175 m) / ((π × (0.023 cm / 2)2) m2)

Finally, we add the resistance of the copper bar and the resistance of the iron bar together to get the total resistance of the welded bar:

Rtotal = Rcopper + Riron