The length of copper wire this motorcyclist must use is equal to 8.56 meters.
<u>Given the following data:</u>
- Voltage of the motorcycle, V = 12 V
- Diameter of the copper wire, d = 0.25 mm
- Current in the wire, I = 4.0 A
Radius, r = diameter/2 = 0.12.5 mm = 0.000125 m.
Resistivity of the copper wire, ρ = 1.72 × 10⁻⁸ Ω-m.
<h3>How to determine the
resistance?</h3>
By applying Ohm's law, the resistance of this copper wire can be calculated by using this formula:
R = V/I
R = 12/4
Resistance, R = 3 Ohms.
Mathematically, the resistance of any conductor (wire) in terms of length is given by this formula:
Length = RA/ρ
Length = Rπr²/ρ
Length = [3 × 3.142 × (0.000125)²]/1.72 × 10⁻⁸
Length = 14.73 × 10⁻⁷/1.72 × 10⁻⁸
Length = 8.56 meters.
Read more on resistance and length here: brainly.com/question/13930397
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