Level 5 · Science S5.14

Electric circuits and capacitors

Circuits follow rules about charge and energy, and capacitors store charge for later.

Planned. This book is not written yet. Below is its plan, which a teacher can already use.

You are ready for this book if

You can use V equals I times R to find a missing value.

The plan

  1. S5.14.1 Resistivity
    • Calculate resistance from resistivity, length and area
    • Explain superconductivity and its uses
  2. S5.14.2 Kirchhoff's laws
    • Apply Kirchhoff's laws to circuits with several loops
    • Explain each law as conservation of charge or of energy
  3. S5.14.3 Potential dividers
    • Calculate output voltages from a potential divider
    • Design a sensor circuit with a thermistor or a light sensor
  4. S5.14.4 Electromotive force and internal resistance
    • Explain the difference between electromotive force and terminal voltage
    • Find internal resistance from a graph of voltage against current
  5. S5.14.5 Capacitors
    • Explain how a capacitor stores charge and energy
    • Calculate capacitance, charge and stored energy
  6. S5.14.6 Capacitors in series and parallel
    • Calculate total capacitance in series and in parallel
    • Explain how a dielectric increases capacitance
  7. S5.14.7 Charging and discharging
    • Use the time constant in the equations for charge and discharge
    • Find the time constant from a graph
  8. S5.14.8 Using capacitors
    • Explain uses such as camera flashes, smoothing and backup power
    • Compare capacitors with batteries for storing energy

For parents and teachers

Level 5 fits learners who can already: read a textbook. use functions and graphs. In many schools that is about 17 to 20, but start wherever the learner is.

Strand: Electricity and magnetism. Written and drawn by attnom. Free to read, print and share.