2ρd1 = l12
or
l12 e H
d1 = ----- --- --- (1).
2 m V
If the rays pass through a uniform electric field of strength X and length l2 with a deviation d2,
1 Xel22
d2 = --- ----- (2),
2 mV2
since Xe/m is the acceleration of the particle, at right angles to its direction, and l2/V is the time required to travel through the electric field.