A mass spectrometer uses sulfur isotopes of mass numbers 32, 33, and 34 from a meteorite sample. The directions of the electric field between the plates and the magnetic fields are shown below. The marks formed by singly charged ions of each type on a detector film are equally spaced based on this expression: $2r=\frac{2mE}{qBB^{\prime }}$. Does it matter if the ion charge is positive (lost electrons) or negative (gained electrons)? Explain.

• A. Yes, the spacing between marks will be different for positive and negative ions.
• B. Yes, positive ions will be detected with the same spacing, but negative ions will not be detected.
• C. No, the spacing between marks will be the same for both positive and negative ions.
• D. No, the direction of deflection will change, but the spacing will remain the same.

Answer: (A)