When a stream of electrons enters an electric field, it experiences a force due to the interaction between the electric field and the electrons' electric charge. The direction of the force is determined by the polarity of the electric field and the charge of the electrons.

Electrons, being negatively charged particles, will experience a force in the opposite direction of the electric field. This means that the electrons will be accelerated in the direction opposite to the electric field lines.

Therefore, in the presence of an electric field, a stream of electrons will be deflected and its trajectory will be altered. The exact path of the electrons will depend on the strength and direction of the electric field, as well as the initial velocity and direction of the electron stream.