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FIG. 29·6 (c) Determining the direction of the magnetic field at the center C due to the current in the wire
An application of the right-hand rule anywhere along the wire shows that all the differential fields dB have the same direction at C directly out of the page.
The total field at C is the sum of all the differential fields dB use the identity ds = Rd to change the variable of integration from ds to d
from Eq. 29-8,
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Scientists medical researchers physiologists
would like to understand how the human brain works.
MEG magnetoencephalography a procedure
magnetic fields of a person's brain monitored as the person performs a task reading a word.
Task activates part of the brain processes reading causing weak electrical pulses sent along conducting paths between brain cells each pulse produces a magnetic field.
FIG. 29·7 A pulse along a fissure wall on the brain surface produces a magnetic field at point P at distance r.
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The path of the pulse tangent the brain surface the angle in Eq. 29-1 is 90°.
The magnetic fields detected in MEG at a point P located a distance r = 2 cm from the pulse i = 10 µA, ds=
1mm
A very small magnetic field more than a million times weaker than Earth's magnetic field cannot detect by hold a compass near the brain and hope that brain activity will turn the compass needle
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