Coil or No Coil?

nanobyte

Joined May 26, 2004
120
h34r: What's up y'all. I was reading an electronics book(Electronics Technology Fundamentalss-Robert T. Paynter & B.J. Toby Boydell p.281) about inductors and two sentences I read popped a question mark in my head:

1. "The current through a wires produces magnetic lines of force".
2. "When a wire is wrapped in a series of loops called a coil, the lines of force generated by the current add together to form a magnetic field."

Does this mean that a wire has to be wrapped in a coil to produce a magnetic field? If so why? I alway though wire with a current sent through it produced a magnetic field and vice versa regardless if the wire was wrapped in a coil or not.

Firestorm

Joined Jan 24, 2005
353
a current passing throuhg a wire will set up a magnetic field around the wire.therefore a coil doesnt matter. The reverse effect also applies stating that a magnetic field will induce current to flow into a wire....so technically u were right ...If u want to get more indepth, look into electromagnetic induction. i hope this is right and makes sense..lol...l8er

-fire

vineethbs

Joined Nov 14, 2004
56
ok,what we want is an inductance , an inductance shud efficiently store magnetic energy in the frequency region of interest , for audio frequencies and upto microwave frequencies , a wire which is made in the form of a coil can effectively act as an inductance at these frequencies ,at higher freq other geometries are used ,also a coil wud make a larger inductance in a smaller volume than a wire (inductances of wires etc do become predominant at higher freq , remember the transmission line theory )

Firestorm

Joined Jan 24, 2005
353
so was i right at part of my explanation? If not, im gonna jump back on the learning ban wagon lol...thx l8er

-fire

beenthere

Joined Apr 20, 2004
15,819
Hi,

It's easy to demo the magnetic field produced by current through a wire. Pass the wire through a piece of paper so the paper is horizontal and the wire vertical for a couple of inches above and below the paper. Pass current through the wire, and sprinkle iron filings on the paper. They will show the lines of force.

While working with a pulser box meant to stun fish for population sampling, I often saw the two external conductors jump apart with each 200 volt 15 amp pulse. Richard Beach wrote of the conductors tearing out of retaining clips when his old diesel submarine went emergency back full. That was something like 800 volts and 2000 amps.