Transformer principle (induced secondary voltage/current)

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Mutaja
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Homework Statement



Draw a sketch and show/explain how the induced secondary voltage and current "moves" when the primary current "breaks" the instant the switch N is opened. See the attached image below (I apologize for my awful paint job...).

Hand-drawn circuit schematic of an iron-core transformer: a battery and switch N on the primary side, primary coil P, secondary coil S connected to a galvanometer G, with two red arrows marking the primary and secondary windings.


Homework Equations


The Attempt at a Solution


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Well. this isn't much of a solution, but I've found out the following about the magnetic circuit, if I can call it that, while the switch is closed:

Diagram of an iron-core transformer with a primary winding of NP turns on the left (red) and a secondary winding of NS turns on the right (blue), with a dashed green arrow showing magnetic flux Φ circulating through the core, and labels for primary current IP, primary voltage VP, secondary current IS and secondary voltage VS.


How can I explore what happens to the circuit when the switch is opened?

The lectures and lecture notes we have on this subject says nothing about this particular problem - or at least I don't understand it.

Any input will be greatly appreciated, thanks.
 
Attachments
  • Hand-drawn circuit schematic of an iron-core transformer: a battery and switch N on the primary side, primary winding P, secondary winding S connected to galvanometer G, with two red arrows marking the induced current direction.
    Magnetic circuit.png
    1.8 KB · Views: 616
  • Diagram of an iron-core transformer with a primary winding of N_P turns on the left and a secondary winding of N_S turns on the right, labelled with primary current I_P, primary voltage V_P, secondary current I_S, secondary voltage V_S, and a dashed green arrow showing magnetic flux Φ circulating through the core.
    Magnetic flux.PNG
    16.6 KB · Views: 602
This is similar to how a flyback transformer works. Try looking that up on wikipedia or other web learning resource.

Since current can't change instantaneously through an inductor, something happens very quickly when the switch opens. You need to keep in mind the real properties of a transformer, including winding capacitance...