Consider the fields near the following and how they might be useful.

i. A long current carrying wire ii. A single loop of current carrying wire iii. Helmholtz coils

iii. A solenoid iv. A single bar magnet v. 2 bar magnets with large pole faces and with the N pole of one facing the S pole of

the other

Which of these sources of magnetic fields might be useful for the following? Explain why you made this choice.

A. In a magnetic susceptibility experiment, you need to place a long thin sample in a magnetic field that varies along the length of the sample.

B. In a mass spectrometer you need to make ions move in arcs of a circle in one plane.

C. In an NMR apparatus you need to have the sample in a tube in both a uniform field perpendicular to the tube axis and a uniform field along its axis. (You will need 2 of the above).