Find resistance of copper wire.

In summary, the resistance of a 1.4 m length of copper wire with a diameter of 5*10^-3 m can be calculated using the equation R = p(L/A), where p is the resistivity of copper, L is the length, and A is the area. After plugging in the values, the correct answer is 1.2*10^-3 Ohm, as confirmed by other similar questions. The discrepancy in the online quiz was due to a faulty database.
  • #1
Spoonerz
5
0

Homework Statement


Find the resistance of a 1.4 m length of copper wire with diameter of 5*10^-3 m.

Homework Equations


R = p(L/A) where p = resistivity of copper, L = length, A = area

The Attempt at a Solution


The resistivity of copper is (1.69 * 10^-8). Radius is d/2 (5*10^-3) / (2) = (2.5*10^-3)
With the radius, the Area A = pi(2.5*10^-3)^2 = (1.96*10^-5).

Plugging it into the equation R = p(L/A)
(1.69*10^-8)*(1.4) / (1.96*10^-5) = (1.2*10^-3) Ohm

There were two similar questions like this where the same approach yield me the correct answer. Somehow this answer I get is incorrect. What am I doing wrong?

On a side note, how many questions may I post?
 
Physics news on Phys.org
  • #2
Spoonerz said:
Plugging it into the equation R = p(L/A)
(1.69*10^-8)*(1.4) / (1.96*10^-5) = (1.2*10^-3) Ohm

1.2*10^-3 Ohm is the correct answer after all. It was just the faulty database in the online quiz. =D
 
  • #3
Spoonerz said:
1.2*10^-3 Ohm is the correct answer after all. It was just the faulty database in the online quiz. =D

Ouch, that hurts! Glad you got it sorted out.
 

1. What is resistance?

Resistance is a measure of how difficult it is for electric current to flow through a material. It is represented by the symbol "R" and is measured in units called ohms.

2. How is resistance calculated?

Resistance is calculated using Ohm's law, which states that resistance (R) is equal to the ratio of voltage (V) to current (I). Mathematically, this can be written as R = V/I.

3. Why is it important to find the resistance of copper wire?

Copper wire is a commonly used material in electrical circuits, so it is important to know its resistance in order to properly design and operate these circuits. Additionally, the resistance of copper wire can change with temperature, so it is important to monitor and account for this change in certain applications.

4. What factors affect the resistance of copper wire?

The resistance of copper wire is affected by the length, thickness, and temperature of the wire. Thicker wires have lower resistance, while longer wires have higher resistance. Additionally, as the temperature of the wire increases, its resistance also increases.

5. How can I measure the resistance of copper wire?

You can measure the resistance of copper wire using a multimeter, which is a device that measures voltage, current, and resistance. Simply connect the ends of the wire to the appropriate ports on the multimeter and it will display the resistance in ohms.

Similar threads

  • Introductory Physics Homework Help
Replies
2
Views
648
  • Introductory Physics Homework Help
Replies
2
Views
1K
  • Engineering and Comp Sci Homework Help
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
978
  • Introductory Physics Homework Help
Replies
6
Views
2K
  • Introductory Physics Homework Help
Replies
14
Views
4K
  • Introductory Physics Homework Help
Replies
3
Views
256
  • Introductory Physics Homework Help
Replies
5
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
3K
  • Introductory Physics Homework Help
Replies
26
Views
2K
Back
Top