KS5 DC Circuits

Back to Teaching Rota

D.C. Circuits - Objectives


• Practical circuits
• Electromotive force and internal resistance
• Kirchhoff’s laws
• Series and parallel arrangements
• Potential divider
• Electrical energy and power

Learning Outcomes

Candidates should be able to:

  • recall and use appropriate circuit symbols as set out in SI Units, Signs, Symbols and Abbreviations (ASE, 1981) and Symbols and Systematics (ASE, 1995).
  • draw and interpret appropriate circuit diagrams.
  • use the concept that e.m.f. is defined in terms of the energy transferred by a source in driving unit charge round a complete circuit.
  • use energy considerations to distinguish between e.m.f. and p.d.
  • know Energy E = I V t, P = IV, P = I2R, P=V2/R
  • application, e.g. Understanding of high current requirement for a starter motor in a motor car.
  • appreciate that sources of e.m.f. have internal resistance and understand the simple consequences of internal resistance for external circuits.
  • recall and use ε = E/Q and ε = I (R + r)
  • differentiate between emf and terminal pd
  • understand and perform calculations for circuits in which the internal resistance of the supply is not negligible
  • Applications; e.g. low internal resistance for a car battery.
  • Conservation of charge and energy in simple dc circuits.
  • recall Kirchhoff’s first law and appreciate this as a consequence of conservation of charge.
  • understand Kirchhoff’s second law as a consequence of conservation of energy.
  • The relationships between currents, voltages and resistances in series and parallel circuits, including cells in series and identical cells in parallel.
  • recall and use a formula for the combined resistance of two or more resistors in series: RT = R1 + R2 + R3 + …
  • recall and use a formula for the combined resistance of two or more resistors in parallel: 1/RT = 1/R1 + 1/R2 + 1/R3 + …
  • understand the use of a potential divider as a source of constant or variable p.d.; e.g. application as an audio volume control
  • describe and explain the use of variable resistors, thermistors and light-dependent resistors in potential dividers to provide a potential difference which is dependent on temperature and on light intensity respectively.
  • REQUIRED PRACTICAL - investigation of the emf and internal resistance of electric cells and batteries by measuring the variation of the terminal pd of the cell with the current in it

Back to Teaching Rota