Imagine a copper wire 10 km long that needs to supply a city with 10 Mwatts of power--say from a waterfall. If the city ran on DC power, with voltages of 100 V, how much current would run through that wire? If you were willing to lose 1% of your power as heat in the wire, how thick would such a wire have to be? The resistivity of copper is 1.7 x 10-8 ohm-m.

The electric potential a distance r from a small charge is proportional to what power of the distance from the charge? a. r^-1 b. r c. r^-2 d. r^2

The solid that is formed and usually sinks to the bottom of a solution is the

Currents in dc transmission lines can be 100 a or higher. some people are concerned that the electromagnetic fields from such lines near their homes could pose health dangers. for a line that has current 150 a and a height of 8.0 m above the ground, what magnetic field does the line produce at ground level? express your answer in teslas and as a percentage of the earth’s magnetic field, which is 0.50 g. is this value cause for worry?