Fig. 28.
If a magnetic field is superimposed parallel to the electric field by means of an electromagnet, a magnetic spectrum is obtained perpendicular to the electric spectrum. The combination of the two spectra gives rise to a curved line on the plate. The double trace obtained on the photographic plate with reversal of the magnetic field is shown in [Fig. 28]. Disregarding some small corrections, it can readily be shown that if y and z are the electric and magnetic deviations respectively,
z
β = κ1 ----- (3),
y
and
e z2
-- = κ --- (4).
m y