A20-cm long and 1.0-mm diameter thick copper wire (resistivity 1.7 × 10-8 ωm) is connected across a 3-v battery. the current through the wire is
1-7 a.
2-125 a.
3-693 ma.
4-693 a.
5-789 a.

We use the ohm's law to be able to calculate things for this problem. We know that V=IR. We use this equation as follows:

now we have V=3V

R=(resistivity*length)/area of cross section of the wire
R = 1.7 × 10-8(.20) / π(0.0005)² = 4.33 x 10 -3

I = V/R = 3 / 4.33 x 10 -3 = 693 A < OPTION 4

Arise 8 run 1 this means go 8 up and 1 across, which is steepest

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