A. What diameter of copper wire (p=2.65x10^8 omega x m) should be used so that a

Question

A. What diameter of copper wire (p=2.65x10^8 omega x m) should be used so that a 15.0m length will have a resistance of 0.26 omega? B. Find the temperature coefficient of resistivity for this wire if an increase in temperature of 120 degrees Celsius changes the resistance from 0.26 omega to 0.38 omega A. What diameter of copper wire (p=2.65x10^8 omega x m) should be used so that a 15.0m length will have a resistance of 0.26 omega? B. Find the temperature coefficient of resistivity for this wire if an increase in temperature of 120 degrees Celsius changes the resistance from 0.26 omega to 0.38 omega B. Find the temperature coefficient of resistivity for this wire if an increase in temperature of 120 degrees Celsius changes the resistance from 0.26 omega to 0.38 omega

Explanation / Answer

A)

R=rho*l/A

A=rho*l/R

pi*r^2=rho*l/R

radius r=sqrt(rho*l/pi*R)

here,
resistivity of copper is rho=1.72*10^-8 ohm*m

r=sqrt(1.72*10^-8*15/3.14*0.26)

=5.621*10^-4 m

=0.5621 mm

diameter d=2*r

d=2*5.621*10^-4

=11.243*10^-4 m

=1.124 mm ....is answer

B)

alpha=(R2-R1)/R1*(dT)

=(0.38-0.26)/(0.26*120)

=3.846*10^-3 oC^-1 ........is answer

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