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CIE iGCSE Physics 4.2.1 Electric charge Study Notes

CIE iGCSE Physics 4.2.1 Electric charge Study Notes -2025-2028 Syllabus

CIE iGCSE Physics 4.2.1 Electric charge Study Notes

CIE iGCSE Physics 4.2.1 Electric charge Study Notes at  IITian Academy  focus on  specific topic and type of questions asked in actual exam. Study Notes focus on CIE iGCSE Physics syllabus with Candidates should be able to:

Core: –

  1. State that there are positive and negative charges
  2. State that positive charges repel other positive charges, negative charges repel other negative charges, but positive charges attract negative charges
  3. Describe simple experiments to show the production of electrostatic charges by friction and to show the detection of electrostatic charge
  4. Explain that charging of solids by friction involves only a transfer of negative charge (electrons)
  5. Describe an experiment to distinguish between electrical conductors and insulators
  6. Recall and use a simple electron model to explain the difference between electrical conductors and insulators and give typical examples

Supplement: –

  1. State that charge is measured in coulombs8 Describe an electric field as aregion in whichan electric charge experiences a force
  2. State that the direction of an electric field at apoint is the direction of theforce on a positivecharge at that point
  3. Describe simple electric field patterns, includingthe direction of the field:
    (a) around a point charge
    (b) around a charged conducting sphere
    (c) between two oppositely charged parallel conducting plates (end effectswill not beexamined)

CIE iGCSE  Physics Study Notes- All Topics

Types of Charges & Charge Transfer

  • Two types of charges:
    • Positive (+) and Negative (-).
  • Charge interactions:
    • Like charges (+ & + or – & –) repel.
    • Opposite charges (+ & –) attract.
  • Subatomic charges:
    • Protons → Positive charge.
    • Electrons → Negative charge.
  • Charge production by friction:
    • Rubbing transfers electrons between materials.
    • Example:
      • Rubbing a balloon against hair.
      • Hair loses electrons, balloon gains them → Balloon sticks to the wall.

Electric charge

  • Objects can have positive or negative charges.
  • Like charges repel, opposite charges attract.
  • Electric charge is measured in Coulombs.
  • Electric charges create electric fields in surrounding areas.
    • Electric field: A region where an electric charge experiences a force.
    • Field lines:
      • Move away from positive charges and towards negative charges.
      • Electrons are negatively charged particles.
        • Negative charge: Gained electrons.
        • Positive charge: Lost electrons.
  • Conductors: Materials that allow charge to pass through (e.g., copper, iron).
  • Insulators: Do not allow charge to pass through (e.g., plastic, wood, rubber).
 
 

Induction

  • When a charged material is brought near an uncharged material, it induces a charge in the uncharged material.
  • Negatively charged rod near an object:
    • Attracts positive charges towards itself.
    • Negative charges gather on the opposite side.
  • Positively charged rod attracts negative charges.

Insulators and Conductors

  • Conductors:

    • Have a pool of delocalized free electrons that move to transfer charges.
    • Electrons can move around different atoms.
    • Examples: Copper, gold, etc.

  • Insulators:

    • Do not have free electrons to transfer charges.
    • Cannot conduct electricity.
    • Examples: Rubber, plastic, etc.

Patterns of Electric Fields

1. Around a Point Charge
  • The electric field is radial and points in all directions.
  • Strength decreases with distance.
  • It is a vector quantity.

2. Around a Charged Conducting Sphere
  • The electric field is uniform and radially symmetric.
  • Field strength decreases as distance from the sphere increases.

3. Between Two Oppositely Charged Parallel Conducting Plates
  • Oppositely charged plates create an electric field between them.
  • The field exerts a force on charged particles.
  • Strength & direction of the field depend on:
    • Distance between the plates.
    • Magnitude of the charges.

Charging by Friction

  • Rubbing two different insulating materials transfers electrons from one body to another.
  • Example:
    • Rubbing a plastic rod with a cloth transfers electrons from the rod to the cloth.
  • Only electrons (negative charge) transfer during frictional charging, not protons.
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