Two wires of an equal diameter are connected in series to make the resistance of

Question

Two wires of an equal diameter are connected in series to make the resistance of the combination temperature independent. If the temperature coefficients of resistance are ?1 and ?2 with ?1=?2?2 and the resistivities are ?1 and ?2 with ?2=3?1 (at the reference temperature) for the two wires, respectively, what is the corresponding ratio of lengths L1/L2 of the two wires?

and

A copper cable hung on two power poles that are 121 m apart carries a current of 211 A. If the potential difference between the two ends of the cable is 0.400 V, what is the weight of the cable? The resistivity and density of copper are 1.72

Explanation / Answer

in this question i will explain process because question is not clear.because what is meaning of question mark

resistance of every material changes with respect to temperature

for metals it is positive

for semiconductors negative

R=RT(1+ALPHA*dt)

alpha=temperature coefficient

find resistance of two wires with alpha1,alpha2 respectively

after finding resistance find length ratio with help of resistives rho1,rho2 respectively

formula for resistance is R=rho*L/A

FOR THIS QUESTION

V=IR I= 211 A. V=potential difference between the two ends of the cable is 0.400 V,

R=0.4/211

=1.8957*10^-3

R=rho*L/A

rho=1.72

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