Typical blood velocities in the coronary arteries range from 10 to \(30 \mathrm{~cm} / \mathrm{s}\). An electromagnetic flowmeter applies a magnetic

\(\mathbb{N T}\) field of \(0.25 \mathrm{~T}\) to a coronary artery with a blood velocity of \(15 \mathrm{~cm} / \mathrm{s}\). As we saw in Figure 24.36, this field exerts a force on ions in the blood, which will separate. The ions will separate until they make an electric field that exactly balances the magnetic force. This electric field produces a voltage that can be measured.

a. What force is felt by a singly ionized (positive) sodium ion?

b. Charges in the blood will separate until they produce an electric field that cancels this magnetic force. What will be the resulting electric field?

c. What voltage will this electric field produce across an artery with a diameter of \(3.0 \mathrm{~mm}\) ?