Faraday's Law of Induction
This is part of the HSC Physics course under the topic Electromagnetic Induction.
HSC Physics Syllabus
- analyse qualitatively and quantitatively, with reference to energy transfers and transformations, examples of Faraday's Law and Lenz's Law `\varepsilon = -N (∆\phi)/(∆t)`, including but not limited to:
Faraday's Law of Induction
This video will analyse qualitatively and quantitatively examples of Faraday's Law. It introduces the equation `\varepsilon = -N (∆\phi)/(∆t)`.
Discovery of Electromagnetic Induction
Michael Faraday wrapped wires around opposite ends of a soft iron ring, with one attached to a power source and another to a voltmeter. After the switch is closed, the current through the first wire caused a temporary pulse of induced current to be created in the opposite wire, which was detected by the voltmeter.
This is because the first wire's current created a magnetic field, which caused the free moving electrons (unaffected by potential difference) in the opposite wires to experience a magnetic force.
$$F=qvB\sin{\theta}$$
This movement of electrons creates current. However, after a short while, the movement of electrons will stop as the constant force causes them to end up in a particular extremity of the conductor e.g. one end of a straight conductive rod. Thus, a current is only induced when the magnetic field, experienced by the conductor is changing.
This is called Faraday’s Law of Induction, which states that an emf is induced in a conductor when it experiences change in magnetic flux. In any closed electrical conductor, this emf leads to a current. The magnitude of the emf is proportional to the rate of magnetic flux change. Faster the change, greater the induced current.
$$\varepsilon = -N\frac{∆\phi}{∆t}$$
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