Class 10 > Unit # 17:Introductory Electronics > Deflection of electron in an electric field

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Deflection of Electron in an Electric Field

Deflection of an Electron Beam in an Electric Field

"The beam of high-speed electrons produced by an electron gun can be precisely directed and steered toward a target by passing it through an external electric field."

Rather than physically moving the electron gun itself, the electron beam is efficiently deflected after its creation by directing it between two oppositely charged parallel metal plates. This electrostatic field exerts a transverse force on the moving electrons.

Key Effects of Electric Field Deflection

1. Direction Change: The electron beam bends and changes its direction of travel under the influence of the electrostatic force.
2. Parabolic Trajectory: Because of the constant transverse acceleration experienced between the charged plates, the beam follows a parabolic (curved) path while inside the electric field.
3. Rapid Steering: When subjected to alternating electric fields, the electron beam can change direction millions of times each second (as utilized in oscilloscopes and older displays).
4. Energy and Speed Variation: Depending on the orientation of the field relative to the velocity vector, the energy and speed of the electrons can be increased.
5. Straight-Line Motion After Exit: Upon emerging from the electric field region, the electrons no longer experience transverse forces and continue moving in a straight line toward the target screen.

Physics Principle: The deflection distance depends on the strength of the electric field, the potential difference across the deflecting plates, and the initial kinetic energy of the incoming electrons.

Fig: Deflection of an electron beam following a parabolic path between two oppositely charged parallel metal plates.

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