Question

the first four coils are made of copper with resistivity of p=1.72 E-8. the fifth coil is made of an alloy called German silver of p= 28.0 E-8 ohmes. the first second and fifth coils are 10 m long. the third and fourth are 20 m. the diameters of the first third and fifth are .0006439 m and the diameter of Second and fourth coils are .0003211. how do you calculate the resistance for each of the five coils. pl/a

Answer 1

for better understanding

SINCE R =pl/a

p=resistivity

l =length

a = area

coil 1,

p=1.72*10^-8, l=10m, d=.0006439m, area(a)=(3.14*D^2)/4=3.2563*10^-7,

R1=5.282*10^-1ohm

coil 2

p=1.72*10^-8 ,l=10m, d=.0006439m, area(a)=(3.14*D^2)/4=3.2563*10^-7,

R2=5.282*10^-1ohm

coil 3

, p=1.72*10^-8, l=20m, d=.00032111m, area=8.0978*10^-8,

R3=4.248ohm

coil 4,

p=1.72*10^-8, l=20m, d=.0003211m, area=8.0978*10^-8,

R4=4.248ohm

coil 5,

p=28*10^-8, l=10m, d=.0006439m, area=3.256*10^-7m^2,

R5=8.5986ohm.