3. You bought an old house and decide to rewire it. You visit the local home-har

Question

3. You bought an old house and decide to rewire it. You visit the local home-hardware store to purchase 1 500m copper wire with a specific resistance (resistivity) of pc 1.68. 10 8?m and a diameter of = 0.5cm. (a) What is the resistance of the entire spool of wire? (b) A friend offers you a different copper wire for free. This wire is specified to have a resistance of 1002 per 100m length. Calculate the radius of this wire assuming the same resistivity as before Would you take your friend's offer? Explain why or why not!

Explanation / Answer

(a) Length =500m Area = 3.14 x 0.0025 x 0.0025 = 1.9625 x 10-5

Total Resistance = pCu x Length/Area = 1.68 x 10-8 x 500 / (1.9625 x 10-5)

Tota resistance = 0.84 Ohm

(b) Resistance of the wire offered by friend = 100/100 = 1 Ohm

Resistivity = Resistance x Area/ Length

1.68 x 10-8 = 1 x Area/ 100

Area = 1.68 x 10-6

3.14 x r2 = 1.68 x 10-6

r = 0.731 mm

No I would not take my friends offer as the the wire has higher resistnace thus greater loss of energy and higher bill amount.

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.