2.1.2 Behaviour of Electron, Proton and Neutron in Electric Field

This topic explains how electrons, protons, and neutrons behave when they pass through an electric field. It describes the forces acting on them and the paths they follow.

Definition

Electric Field: A region around a charged particle where a force is exerted on other charged particles.

Main Idea

In an electric field, electrons and protons undergo opposing forces due to their opposite charges. Electrons (negative) move towards the positive pole, while protons (positive) move towards the negative pole. Neutrons (neutral) experience no force and pass undeflected. When particles share the same velocity, their paths diverge due to the electric forces acting on them.

Core Concept

The behavior of sub-atomic particles in an electric field depends on their charge and mass. Opposite charges attract, like charges repel, and neutral particles are unaffected. The amount of deflection depends on the charge-to-mass ratio.

Detailed Explanation

Behavior of Sub-Atomic Particles

• Negatively charged.
• Move against the electric field towards the positive pole.
• Deflected more than protons because of their much smaller mass.

• Positively charged.
• Move in the direction of the electric field towards the negative pole.
• Deflected less than electrons due to their larger mass.

• No charge.
• Experience negligible forces.
• Exhibit no deviation in an electric field.

When Particles Share the Same Velocity

• Their paths diverge due to the electric forces acting on electrons and protons.
• Electrons curve against the electric field.
• Protons curve with the electric field.
• Neutrons, having no net charge, continue along their path with minimal deflection.
• The turning curvature also depends on the trajectory force or velocity.

Key Observations

• Electron (e⁻): Deflected much more than the proton (p⁺) as it has a much smaller mass.
• Proton (p⁺): Deflected less than the electron due to its larger mass.
• Neutron (n): No deflection — continues straight.

Intermediate Level

Electric Field

- A region where charged particles experience a force.

Behavior

• Electron: Negative charge → attracted to positive pole → curves against the field → deflects more (small mass).
• Proton: Positive charge → attracted to negative pole → curves with the field → deflects less (large mass).
• Neutron: No charge → no force → no deflection.

Key Point

• The amount of deflection depends on the charge-to-mass ratio.
• Electron has a high charge-to-mass ratio → more deflection.
• Proton has a low charge-to-mass ratio → less deflection.

Comparison Table

Important Points

• 1. Electrons move towards the positive pole.
• 2. Protons move towards the negative pole.
• 3. Neutrons are undeflected.
• 4. Electrons deflect more than protons due to smaller mass.
• 5. Deflection depends on charge-to-mass ratio.
• 6. Electrons and protons follow parabolic paths.
• 7. Neutrons follow straight paths.

Remember

• - Electron: Negative → positive pole → more deflection
• - Proton: Positive → negative pole → less deflection
• - Neutron: Neutral → no deflection
• - Deflection depends on: Charge-to-mass ratio

Common Mistakes

• 1. Thinking electrons and protons deflect the same: Electrons deflect more due to smaller mass.
• 2. Forgetting neutrons are undeflected: They have no charge.
• 3. Confusing the direction of deflection: Electrons → positive pole; Protons → negative pole.
• 4. Ignoring the role of mass: Both charge and mass affect deflection.

Quick Revision

• Electrons move towards the positive pole.
• Protons move towards the negative pole.
• Neutrons are undeflected.
• Electrons deflect more than protons due to smaller mass.
• Deflection depends on charge-to-mass ratio.

60-Second Revision

• Electron: Negative → positive pole → more deflection
• Proton: Positive → negative pole → less deflection
• Neutron: Neutral → no deflection
• Deflection depends on: Charge-to-mass ratio

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