Parallel currents attract, opposite currents repel
The Electromagnetic Flowmeter
The probe’s magnets apply a strong field. The electrodes make contact along an axis
perpendicular to this field.
The magnetic field exerts forces on ions moving with the blood. Positive and negative
ions feel forces in opposite directions.
These forces create a separation of charge, producing a potential difference between
If the flow is north at 3.5 m/s, the field is tipped at a 60° angle, and an investigator places two
electrodes 10 m apart, on an east-west axis, what is the measured voltage?
B y 50μT sin 60°
qE = qvB
E = vB
E = (3.5 m/s) (50 μT sin 60°)
E = 1.5 x 10 V/m
ΔV = EΔd = (1.5 x 10 V/m) (10 m) = 1.5