Using an electromagnetic flowmeter (see the figure below), a heart surgeon monit

Question

Using an electromagnetic flowmeter (see the figure below), a heart surgeon monitors the flow rate of blood through an artery. Electrodes A and B make contact with the outer surface of the blood vessel, which has interior diameter 2.95 mm.
(a) For a magnetic field magnitude of 0.0395 T, a potential difference of 160 V appears between the electrodes. Calculate the speed of the blood. m/s
(b) Verify that electrode A is positive, as shown. Does the sign of the emf depend on whether the mobile ions in the blood are predominantly positively or negatively charged? Explain.
This answer has not been graded yet. Using an electromagnetic flowmeter (see the figure below), a heart surgeon monitors the flow rate of blood through an artery. Electrodes A and B make contact with the outer surface of the blood vessel, which has interior diameter 2.95 mm.
(a) For a magnetic field magnitude of 0.0395 T, a potential difference of 160 V appears between the electrodes. Calculate the speed of the blood. m/s
(b) Verify that electrode A is positive, as shown. Does the sign of the emf depend on whether the mobile ions in the blood are predominantly positively or negatively charged? Explain.
This answer has not been graded yet. Using an electromagnetic flowmeter (see the figure below), a heart surgeon monitors the flow rate of blood through an artery. Electrodes A and B make contact with the outer surface of the blood vessel, which has interior diameter 2.95 mm.
(a) For a magnetic field magnitude of 0.0395 T, a potential difference of 160 V appears between the electrodes. Calculate the speed of the blood. m/s
(b) Verify that electrode A is positive, as shown. Does the sign of the emf depend on whether the mobile ions in the blood are predominantly positively or negatively charged? Explain.
This answer has not been graded yet.

Explanation / Answer

a) The ions move along the vessel while the magnetic force is transverse to the vessel. The redistritbution of ions results in a transverse electric field resulting in a force on the ions in the opposite direction.

the speed of the ions must be,

v=E/B=V/Bd=160 V/ (0.0395T*2.95 mm) = 1.37 m/s

b) Consistent with the right hand rule, the direction of the magnetic force exerted on the ions with a positive charge is upward while the force exerted on the negatively charged ions is downward. In both cases, the polarity of the electric field is consistent with the indicated potential of the electrodes. Both types of ions contribute to the electromotive force.

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