13 Direct current circuits

This section is about applying some more advanced rules to circuits that build on your GCSE skills. The trick is to realise that you must be 100% logical and treat it as a mathematical exercise. If you set up the problems correctly then you cannot go wrong. Take note of these things that you must be able to do…

  1. Make sure you treat current and pd as having a direction.
  2. Learn how to apply reciprocal equations for 1/R for resistors in parallel
  3. Learn what the gradient and intercept mean on an Internal Resistance circuit graph
  4. Remember that a power source is a “real source” and will get warm so lose energy! A 3V cell does not output 3V!
  5. When thinking about potential dividers the trick is to realise that current is the same through each resistor. So setup two equations for V for each then I is the same for both!


13 DC Circuits (Main PPT Updated!)

13 DC Circuits Student Booklet (student booklet notes + PPT selected slides)

Donkey_Model  (Think about how a model might help you?)

13.1 Circuit rules

 5_1_kirchoffs laws (problem sheet)

13.2 More about resistance

5_2_Practical_investigating_resistors (Practical on Resistors)

 5_2_practical_cons_energy (Practical sheet proving Kirchhoff’s laws)

resistor_cube_problem (Extension – 3D resistor cube problem – for fun!)

13.3 Emf and internal resistance

Internal Resistance Calculator (Hyper Physics)

5_3_EHT_Practical_Demo (teacher demo with results to graph)

5_3_Internal_Resistance Problems (problems sheet)

5_3_IR_of_Battery variable current method (practical method 1)

5_3_IR_of_Cell adding bulbs method (practical method 2)   Results 3 Cells (excel results)


 5_3_IOP_notes  (extra reading from IOP)

13.4 More circuit calculations

5_4_Investigation_cell_combinations (Crucial practical which explores how PD behaves for series & parallel)

13.5 The potential divider

5_4_Potential_Dividers Worksheet


Youtube Video Tutorials “Electricity” – Steve4Physics
E10 Kirchhoff’s First Law
E11 Kirchhoff’s Second Law
E12 Resistors in series
E13 Resistors in parallel
E14 The resistance of series and parallel resistor combinations
E15 Internal Resistance 1 of 4
E16 Internal Resistance 2 of 4
E17 Internal Resistance 3 of 4
E18 Internal Resistance 4 of 4
E19 Potential (Voltage) Dividers
E20 Potentiometers
E21 Power in Electrical Circuits – Part 1 of 2
E22 Power in Electrical Circuits – Part 2 of 2
E25 Resistance and Temperature 1 of 3
E26 Resistance and Temperature 2 of 3. Semiconductors
E27 Resistance and Temperature 3 of 3 Superconductors
E28 Circuits – Problem Solving

Kirchhoff's Laws - A-level Physics

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00:00 Kirchhoff's 1st & 2nd laws
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