9478 / 2027

Chapter 14

Electric Fields

Choose the source, test charge, direction and reference before using an electric-field or energy equation.

Explain electric interactions with consistent signs and use field and energy models to calculate motion and capacitor behaviour.

Point-charge force and field, electric potential and pair energy, potential gradients, uniform plate fields, charged-particle deflection, capacitance and stored energy. For 9478 (2027).

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  1. Point-charge force and field

    Distinguish a source field from the force on a test charge and use charge signs with Coulomb's law.

  2. Electric potential and energy

    Use an infinity reference and distinguish potential per charge from the signed interaction energy of a pair.

  3. Field from a potential gradient

    Use a local tangent and its negative sign, and distinguish vector field sums from scalar potential sums.

  4. Uniform fields between plates

    Calculate a plate field from perpendicular separation and determine force directions for signed charges.

  5. Charged-particle motion

    Connect electric force to component acceleration, a calculated exit state and subsequent force-free motion.

  6. Capacitance and plate charge

    Define capacitance, distinguish plate-charge magnitude from net charge, and interpret a linear Q-V record.

  7. Energy stored in a capacitor

    Derive stored energy from the V-Q area and compare changes at fixed charge or fixed voltage.