# Resistance Problem Find Length of Wire

• m_physics
The correct conversion is 0.00044m. Therefore, the correct length of the wire is 0.17m. In summary, the current, potential difference, and diameter of a copper wire were given. The correct length of the wire was calculated using the equations V=IR and R=row(L/A), with the resistivity of copper being 1.72 x 10^-8. The conversion of the diameter from millimeters to meters was corrected, resulting in a final wire length of 0.17m.
m_physics
1.Problem
A current of 0.76A flows through a copper wire 0.44mm in diameter when it is connected to a potential difference of 15V. How long is the wire?

2. Homework Equations (Missing any?)
V=IR
R=row(L/A)
A=pieD^2/4
row=resistivity=p
p of copper=1.72 x 10^-8

3.Attempt
Pretty sure conversion is wrong.
V=IR
15=(.76a)R
R=19.737

D=.44mm mm to m
4.4 x 10^-5m

A=pieD^2/4
A=(3.14)(4.4 x 10^-5)^2/4
A=1.512 x 10^-9

Plug back into the resistance equation for L

R=row(L/A)R=row
19.737=(1.72 x 10^-8)(L/1.512 x 10^-9)
2.999x10^-8=1.72 x 10^-8L
L=(2.999x10^-80)/(1.72 x 10^-8)
L=1.744m

You made an error in converting the diameter of the wire from millimeters to meters.

## 1. How does the length of the wire affect resistance?

The length of a wire affects resistance because the longer the wire, the higher the resistance. This is because as the length increases, the number of atoms and collisions that electrons encounter also increases, making it more difficult for the electrons to flow through the wire.

## 2. What is the formula for calculating resistance?

The formula for calculating resistance is R = ρ * (L/A), where R is resistance, ρ is the resistivity of the material, L is the length of the wire, and A is the cross-sectional area of the wire.

## 3. How do you conduct an experiment to find the resistance of a wire?

To find the resistance of a wire, you will need a power source, a voltmeter, and an ammeter. Connect the wire to the power source and measure the voltage across the wire using the voltmeter. Then, measure the current flowing through the wire using the ammeter. Finally, use the formula R = V/I to calculate the resistance.

## 4. Why is it important to consider the material of the wire when calculating resistance?

The material of the wire is important because different materials have different resistivity values. For example, copper has a lower resistivity than iron, which means it will have a lower resistance for the same length and cross-sectional area. Therefore, the material of the wire will affect the overall resistance of the wire.

## 5. How can the resistance of a wire be reduced?

The resistance of a wire can be reduced by either decreasing the length of the wire or increasing the cross-sectional area. This will decrease the number of collisions and obstacles that electrons encounter, making it easier for them to flow through the wire. Additionally, using a material with a lower resistivity can also reduce the resistance of the wire.

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