A magnetic field set up using Helmholtz coils (described in Exercise 4.16) is uniform in a small region and has a magnitude of 0.75 T. In the same region, a uniform electrostatic field is maintained in a direction normal to the common axis of the coils. A narrow beam of (single species) charged particles all accelerated through 15 kV enters this region in a direction perpendicular to both the axis of the coils and the electrostatic field. If the beam remains undeflected when the electrostatic field is `9.0xx10^(-5)Vm^(-1)`, make a simple guess as to what the beam contains. Why is the answer not unique ?

Explanation

Deuterium ions or deuterons, the answer is not unique because only the ratio of charge to mass is determined. Other possible answers are `He^(++) , Li^(+++) `, etc