Does My Bike Induce Electricity?

An anonymous reader asks: "I have a steel frame road bicycle and recently began riding on a path that parallels high-tension power lines for several miles. My question is: Does my bike induce an electric current by passing through the electric fields from the power lines? I normally ride the section at about 18 miles per hour, estimate the distance to the lines at about 75-100 feet, and think they're 200KV lines."

Comments

Depends

[pclminion]

If the lines are AC (which is the usual case except for long distance transmission lines) then you should have an induced emf in the bike frame. The bike frame forms a conducting loop, and as the AC current oscillates in the transmission line it creates a magnetic field perpendicular to the wire, which oscillates at the same frequency. As this magnetic field passes through the bike frame loop it will induce an alternating current at the same frequency. Basically your bike frame is acting like a single-turn inductor.

You can increase the induced emf by wrapping multiple turns of insulated magnet wire into a loop in the same orientation as the bike frame. Neglecting the finite resistivity of the wire, you will get twice as much emf every time you double the number of turns. But even with hundreds of turns we're still talking about millivolts or perhaps hundredths of a volt at most.

If the line is DC, then there will be no induced emf since the magnetic field is not changing.

The speed at which you ride the bike has no influence on the induced emf, unless you are travelling near light speed, in which case the apparent frequency of the AC will be reduced since you are "catching up" to the propagating waveform. But I don't think you could pedal that fast :-)