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Conservation of charge
Beginner
Total charge in an isolated system is constant.
The total charge in an isolated system never changes: charge is neither created nor destroyed, only transferred. It holds even in particle reactions.
In pair production a photon gives +e and −e, total zero.
Net charge, not the number of particles, is conserved.
In more detail
Charge is conserved: the total electric charge of an isolated system does not change. Charges can be created or destroyed only in pairs with opposite signs.
Real-world uses
- Circuit analysis uses charge conservation to track current at junctions.
- Particle physics checks reactions for charge conservation.
- Chemists balance reactions to show that the total charge of the reactants equals the total charge of the products.
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Frequently asked questions
Can charge be created?
Only as equal positive and negative charges, so the net charge stays zero.
Does conservation apply to chemistry?
Yes, the total charge of reactants equals that of products.
Can charge be created or destroyed?
Not in an isolated system. Charge can only move, or be transferred, between objects.
Related topics in Electrostatics
Electric charge · Conductors and insulators · Charging by friction, contact, induction · Quantisation of charge · Coulomb's law · Coulomb constant