Thomson
wanted to know if all of the positive charge was carried
by particles of the same type, a positive equivalent
of the electron. He used a method which would show whether
there were different types of carriers for the positive
charge.
He
sent a narrow beam of positive rays between two brass
plates and applied an electric field that bent the beam
of charged particles in the XX' direction. He then put coils
at the same point, generating a magnetic field to bend
the beam YY' direction.
