Fetal MEG measures magnetic fields a few billion times weaker than the one that turns a compass needle. Zoom in to see how far apart they are. Each circle is drawn in proportion to the strength of its field.
Select a row to jump there.
| Source | Approximate field | Orders of magnitude below Earth's field |
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A tesla is the unit of magnetic field strength. A microtesla (µT) is a millionth of a tesla, a nanotesla (nT) a billionth, a picotesla (pT) a trillionth, and a femtotesla (fT) a quadrillionth. Each order of magnitude is a factor of ten.
Values are approximate and show typical orders of magnitude. Fields from the body are measured with sensors close to it, and they weaken quickly with distance. Each circle uses one typical value, even where the real range spans a factor of ten or more.