1 Calculate the ressitance per unit length of a thin 22gauge

1. Calculate the ressitance per unit length of a thin 22-gauge Nichrome wire which has a radius of 0.375 mm. If a potential difference of 15V is maintained across a 1.0 m length of the Nichrome wire, what is the current of the wire?(Answers below)

cross-sectional area of the wire = 0.000000442 m^2

resistance per unit length = 3.39 ohm/m.

I=4.424

Using the same problem, calculate the electric field in the wire assuming that the wire carries a current of 7.9 A.

E= --------- N/C

Solution

Resistance = resistivity x length / cross section area

R = rho L / A

resistivity of nivhrome = 1.50 x 10^-6 ohm

R = (1.50 x 10^-6 x 1 ) / pi (0.375 x 10^-3)^2 = 3.58 ohm

I = V/R = 15 / 3.58 =4.19 A ......Ans

E = V/d = 15 / 1 = 15 N/C .......Ans