Wires aren\'t really ideal. The voltage drop across a current-carrying wire can

Question

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 80 ftextension cord is being used to provide power to an electric lawn mower. The cord carries a 11 Acurrent. The copper wire in a typical extension cord has a 1.3 mm diameter.

Part A

What is the voltage drop across a 80 ft length of wire at this current?

Express your answer using two significant figures.

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 80 ftextension cord is being used to provide power to an electric lawn mower. The cord carries a 11 Acurrent. The copper wire in a typical extension cord has a 1.3 mm diameter.

Part A

What is the voltage drop across a 80 ft length of wire at this current?

Express your answer using two significant figures.

Explanation / Answer

length = 80 ft = 24.384 m

Area = pi*0.0013*0.0013/4 = 0.00000132732

rho = 1.7 *10^-8

Resistance = rho*l/A = 1.7*(10^-8)*24.385/0.00000132732 = 0.312 ohm

So voltage drop = IR = 11*0.312= 3.432 V Answer

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