Post by thread:OT: measuring megagauss

I have just been asked, by a desperate person, what instrument will measure magnetic fields in the megagauss range (he's trying to draw a chalk line on the floor saying, do not bring credit cards across this line). What do i tell him to rent??? thanks, alice

Are you sure it is megaGauss? I measure in the milli. ----- Original Message ----- From: "Alice Campbell" <spam_OUT1502amcTakeThisOuTLO.SCSENG.COM> To: <.....PICLISTKILLspam@spam@MITVMA.MIT.EDU> Sent: Wednesday, January 19, 2000 12:08 AM Subject: OT: measuring megagauss | I have just been asked, by a desperate person, what instrument will | measure magnetic fields in the megagauss range (he's trying to | draw a chalk line on the floor saying, do not bring credit cards | across this line). What do i tell him to rent??? | thanks, | alice |

> > | I have just been asked, by a desperate person, what instrument will > > | measure magnetic fields in the megagauss range (he's trying to > > | draw a chalk line on the floor saying, do not bring credit cards > > | across this line). What do i tell him to rent??? > > | thanks, > > | alice For low coercivity credit cards, you need about 300g to affect the data. Inverse square law applies, so at whatever distance you measure 300g, at twice that distance you'll be at 75, and at half, 600. Use a gaussmeter, but beware, the inexpensive probes-meters are single-axis. This means that you will have to turn the probe around in all directions to be sure you have read the strongest vector. Otherwise, get some old credit cards, check them to make sure that they read, and put them on posts at pocket level, at varying distances. Find the farthest one that fails to read properly after exposure, and draw your line at 2x that distance.

How about a fence? Seriously, We have a Gauss meter that is capable of measuring to about 30,000 Gauss, but megagauss? Sounds too powerful to me. Is this guy working with superconducting magnets possibly? Anyway, you might try a company by the name of MAGNETIC INSTRUMENTATION Inc. They are located at 8431 Castlewood Drive, Indianapolis, In. 46250 Phone: (317)-842-7500 Fax: (317)-849-7600 They will be able to tell you what you need and whether or not they have instruments capable of such strengths. Good Luck, Regards, Jim On Wed, 19 January 2000, Steven Rightnar wrote: > > Are you sure it is megaGauss? I measure in the milli. > {Original Message removed}

Wouldn't it be 1200 at half the distance? Jim On Wed, 19 January 2000, Dave VanHorn wrote: {Quote hidden}> > > > | I have just been asked, by a desperate person, what instrument will > > > | measure magnetic fields in the megagauss range (he's trying to > > > | draw a chalk line on the floor saying, do not bring credit cards > > > | across this line). What do i tell him to rent??? > > > | thanks, > > > | alice > > For low coercivity credit cards, you need about 300g to affect the data. > Inverse square law applies, so at whatever distance you measure 300g, at > twice that distance you'll be at 75, and at half, 600. > > Use a gaussmeter, but beware, the inexpensive probes-meters are single-axis. > This means that you will have to turn the probe around in all directions to > be sure you have read the strongest vector. > > Otherwise, get some old credit cards, check them to make sure that they > read, and put them on posts at pocket level, at varying distances. Find the > farthest one that fails to read properly after exposure, and draw your line > at 2x that distance. jimKILLspamjpes.com

part 0 1232 bytes content-type:text/x-vcard; charset=us-ascii; (decoded 7bit) Pailoor Alice Campbell wrote: > > yes, Mega. the magnets are the size of Volkswagens. > > > Are you sure it is megaGauss? I measure in the milli. > > {Original Message removed}

Dave VanHorn wrote: > So can you elaborate on the situation? You've got me interested :) It's a Nuclear Magnetic Resonance (NMR) Imager. To be Politically Correct, now called a MRI ("No Nuclear" you see...) -- Cheers, Paul B.