K323 / 2027

Chapter 15

D.C. circuits

The connections determine which current and voltage relationships apply.

Identify shared paths and endpoints, then solve the circuit one part at a time.

Includes the potentiometer and circuits using an NTC thermistor or an LDR. For K323 (2027) / 6091 (2026).

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Choose a topic

  1. Circuit symbols and connections

    Draw components and identify the same connections in different layouts.

  2. Series circuits

    Explain the shared current, add voltage drops and find total resistance.

  3. Parallel circuits

    Identify equal branch voltages, add branch currents and find effective resistance.

  4. Solving a complete circuit

    Reduce a network, recover individual readings and explain what changes when a branch opens.

  5. Potential dividers and the potentiometer

    Relate the output voltage to the chosen terminals and wiper position.

  6. Thermistor and LDR circuits

    Explain how temperature or light changes resistance and the output of a powered divider.