Extension cords are often made from 18-gauge copper wire (diameter 1.0mm ).

Question

An electric saw that draws 8.0 is operated at the end of an 8.0 -long extension cord. Find the potential difference between the wall outlet and the saw.

Answer 1

The 18awg wire has resistance of 7.7ohms/1000ft. For a wire 8ft lg

the voltage drop is 7.7/1000 x 8ft x 8amps = .49V drop at the saw.

This could increase as the temperature of the wire increases. You're pushing the ampacity of the wire. Depends on the insulation.

Answer 2

For 2 points, I second what "billruss" said.  I'd guess draw 8.0 means amperes, and 8.0 long is in metres, and then look up resistance per metre for 18 AWG copper wire, assuming stranded.

Answer 3

8 what? amps?

8 what? meters, feet?

too many unknowns.

but #18 is 6.4 mΩ per ft

So R = 6.4 mΩ x distance x 2 (2 wires, out and back)

E = IR, multiply current by R to get voltage drop.

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