# Homework Help: Transformer principle (induced secondary voltage/current)

1. Sep 26, 2014

### Mutaja

1. The problem statement, all variables and given/known data

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...).

2. Relevant equations

3. The attempt at a solution

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:

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.

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• ###### Magnetic flux.PNG
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2. Sep 26, 2014

### Staff: Mentor

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....