How does the modifiable values affect on the radius of the circular orbit?

Choose if or in which way the acceleration voltage Va and the coil current I affect the radius of the electrons circular orbit.
diagram of the experimental setup to investigate the deflection of electrons in magtic fields.

Which influence does the current I through the Helmholtz coils have on the radius of the circular orbit?

Which influence does the acceleration voltage Va have on the radius of the circular orbit?