Nichrome wire of cross-sectional radius 0.792 mm is to be used in winding a heat

Question

Nichrome wire of cross-sectional radius 0.792 mm is to be used in winding a heating coil. If the coil must carry a current of 9.75 A when a voltage of 270 V is applied across its ends, find the following. (a) the required resistance of the coil 27.6923076923 ? (This part I got correct) (b) the length of wire you must use to wind the coil in meters I am not sure how to calculate this part. I used a value for resistivity of 1.1*10^-6, but I am not sure if that's right. I used the formula below, but my answer was wrong. L = RA/p Your help would be appreciated. Please show your work so I can figure out how to do this. Thanks.

Explanation / Answer

started to solve this until I saw "270 V"

I can guess at the meaning, but I can't answer a question based on guesses.

format for exponents is 10² or 10^2

edit: use ohm's law to find the resistance, R = 270/9.75=27.89

Then use the following to calculate the length.
Resistance of a wire in
R = L/A
is resistivity of the material in -m
L is length in meters
A is cross-sectional area in m²
A = r², r is radius of wire in m
resistivity Cu 17.2e-9 -m
resistivity Nichrome 150e-8 -m

27.89 = (150e-8)L / (*0.000792²)
L=54932.39/15=3662.15 m

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

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