IIl Irrigation channels that require regular flow monitoring are often equpped w
ID: 1776798 • Letter: I
Question
IIl Irrigation channels that require regular flow monitoring are often equpped with electromagnetic fowaneters in which the magnetic feld is produced by horizontal coils embedded in the bottom of the channel. A particular coil has 100 turns and a diameter of 6.0 m. When it's time for a measurement, a 5.0 A current is turned on. The large diameter of the coil means that the field in the water flowing directly above the center of the coil is approximately equal to the field in the center of the coil. a. What is the magnitude of the field at the center of the coil? b. If the field is directed downward and the water is flowing east, what is the direction of the force on a positive ion in the water above the center of the coil? c. If the water is flowing above the center of the coil at 1.5 m/s, what is the magnitude of the force on an ion with a charge +e?Explanation / Answer
a)We know that the magnetic field at the center of the coil is given by:
B = u0 I/2 R
B = 4 x 3.14 x 10^-7 x 5/(2 x 3) = 5.24 x 10^-6 T
Hence, B = 1.05 x 10^-6 T
b)We know that the velocity, B field and force are perpendicular to each other. So the force will be into the page.
c)We know that force on moving charge is:
F = q v B
F = 1.6 x 10^-19 x 1.5 x 1.05 x 10^-6 = 2.52 x 10^-25 N
Hence, F = 2.52 x 10^-25 N