State that there are positive and negative charges

Published by Patrick Mutisya · 14 days ago

IGCSE Physics 0625 – 4.2.1 Electric Charge

4.2.1 Electric Charge

Objective

State that there are positive and negative charges.

Key Concepts

  • Electric charge is a fundamental property of matter.

  • Charges occur in two types: positive and negative.

  • Like charges repel; unlike charges attract.

  • The unit of charge is the coulomb (C).

Properties of Positive and Negative Charges

PropertyPositive ChargeNegative Charge
Symbol+\$\,\$-\$\,\$
Typical particleProtonElectron
Direction of electric fieldAway from chargeTowards charge
InteractionAttracts negative, repels positiveAttracts positive, repels negative

Quantifying Charge

The charge of a single electron is \$e = 1.602 \times 10^{-19}\,\text{C}\$, which is negative. A proton carries a charge of \$+e\$.

Charge is conserved: the total charge in an isolated system remains constant.

Example

  1. Identify the type of charge on a glass rod rubbed with silk.

  2. Explain why two similarly charged objects repel each other.

Suggested diagram: Two spheres, one labelled + and the other -, showing attraction and repulsion of electric field lines.