I need help on my homework. Thanks! Problem 22.26 A 3.5 V potential difference i

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I need help on my homework. Thanks!

Problem 22.26 A 3.5 V potential difference is applied between the ends of a 0.60 mm -diameter, 55 cm -long nichrome wire. Part A What is the current in the wire? Express your answer using two significant figures. I= Problem 22.55 Wires aren't really ideal. The voltage drop across a current-carrying wire can be significant unless the resistance of the wire is quite low. Suppose a 70 ft extension cord is being used to provide power to an electric lawn mower. The cord carries a 15 A current. The copper wire in a typical extension cord has a 1.3 mm diameter. Part A What is the voltage drop across a 70 ft length of wire at this current? Express your answer using two significant figures.

Explanation / Answer

Given,
Potential Difference V = 3.5 v
Radius of Wire r = 0.6/2 * 10^-3 = 0.3 * 10^-3 m
Length of wire L = 55 * 10^-2 m
Resistivity of nichrome(rho) = 1.10 x 10^-6 ohm/m  
Now ,
R = rho x L/A
R = 1.10 x 10^-6 x 55 x 10^-2/[pi x r^2]
R = 1.10 x 10^-6 x 55 x 10^-2/[3.14 x (0.3 x 10^-3)^2]
R = 6.05 x 10^-7/[2.8 x 10^-7]
R = 2.14 ohm

Now by V = i x R
3.5 = i x 2.16
i = 1.635 amp

Current in the wire i = 1.64 amp

Please post seperate question in sepearate post

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