Conservation of Charge in Physics

Introduction to the Law of Conservation of Charge

• A fundamental and undamaged law in physics.
• States that the total electric charge in an isolated system remains constant.
• No experiment has ever disproven this law.

Explanation through Example

• Consider a closed box containing particles:
  • Particle 1: +2 coulombs
  • Particle 2: -3 coulombs
  • Particle 3: +5 coulombs
• Total charge calculation:
  • 2 + (-3) + 5 = +4 coulombs
• If no charge enters or exits, the total charge remains constant at +4 coulombs.

Importance in Physics

• Particles can change form (e.g., collide and form new particles), but total charge remains unchanged.
• For instance:
  • If initial particles have +4 coulombs combined, any new particles must also total +4 coulombs.

Application in Particle Interactions

• Example: Proton colliding with another particle could result in different particles.
  • Even if new particles have different individual charges, total charge remains the same.
• Key Concept: Charge conservation allows for the prediction and understanding of possible reactions and outcomes.

Calculating Unknown Charges

• Given new particles with charges:
  • Particle A: +1 coulomb
  • Particle B: -7 coulombs
  • Particle C: -4 coulombs
  • Unknown Particle D: q coulombs
• Equation: 1 + (-7) + (-4) + q = 4
• Solve for q: q = +14 coulombs

Real-world Implications

• Example: A particle X with +3 coulombs decays into particles Y and Z.
  • Y: +2 coulombs, Z: -1 coulomb
  • Expected total charge: +3 coulombs
  • If total is not +3, a particle or charge is missing.

Zero Charge Systems

• Particles with zero initial charge can transform:
  • Can result in positive and negative charges that cancel each other out.
• Example: Photon (0 coulombs) can create a pair:
  • Particle with +3 coulombs
  • Antiparticle with -3 coulombs (positron)

Conclusion

• The law of conservation of charge is a powerful tool for analyzing particle reactions.
• Allows physicists to determine the feasibility of certain transformations or reactions based solely on charge conservation.