Using your knowledge of circular (centripetal) motion, derive an equation for the radius r of the circular path that electrons follow in terms of the magnetic field b, the electrons' velocity v, charge e, and mass m. you may assume that the electrons move at right angles to the magnetic field.

2. recall from electrostatics, that an electron obtains kinetic energy when accelerated across a potential difference v. since we can directly measure the accelerating voltage v in this expierment, but not the electrons' velocity v, replace velocity in your previous equation with an expression containing voltage. the electron starts at rest. now solve this equation for e/m.

you should obtain e/m = 2v/(b^2)(r^2)

3. the magnetic field on the axis of a circular current loop a distance z away is given by

b = mu i r^2 / 2(r^2 + z^2)^ (3/2)

where r is the radius of the loops and i is the current. using this result , calculate the magnetic field at the midpoint along the axis between the centers of the two current loops that make up the helmholtz coils, in terms of their number of turns n, current i, and raidus r. helmholtz coils are separated by a distance equal to their raidus r. you should obtain:

|b| = (4/5)^(3/2) *mu *ni/r = 9.0 x 10^-7 ni/r

where b is magnetic field in tesla, i is in current in amps, n is number of turns in each coil, and r is the radius of the coils in meters