Please someone explain how current is induced in the secondary coil even though it is not connected to a voltage source.
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Hi There!
(Refer to diagram below when reading through this)
First you must know what actually induces a voltage (e.m.f) in a conductor, it is a changing magnetic field, put a coil in the area around a current carrying conductor, keep changing the current in the conductor, the field around it changes, and thus the current is induced in the coil, similarly if you move the coil, it changes the magnetic flux linkage thus inducing a current in it.
Now regarding the transformer, a transformer consists of two coils wound around a soft laminated iron core (Figure 1), it works on an a.c current which keeps changing its direction as well as 'amount' continuously according to the a.c current graph (Figure 2), you may know that the current in the primary coil may magnetizes the core, as the current keeps changing the field lines in between as well as the magnetic field in the core keeps changing (due to change in current direction and amount) as a result of this changing magnetic field, the secondary coil (Which is not magnetized) has an e.m.f induced in it due to the changing magnetic field in the core which it is wound.
Hope that Helps!
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(Refer to diagram below when reading through this)
First you must know what actually induces a voltage (e.m.f) in a conductor, it is a changing magnetic field, put a coil in the area around a current carrying conductor, keep changing the current in the conductor, the field around it changes, and thus the current is induced in the coil, similarly if you move the coil, it changes the magnetic flux linkage thus inducing a current in it.
Now regarding the transformer, a transformer consists of two coils wound around a soft laminated iron core (Figure 1), it works on an a.c current which keeps changing its direction as well as 'amount' continuously according to the a.c current graph (Figure 2), you may know that the current in the primary coil may magnetizes the core, as the current keeps changing the field lines in between as well as the magnetic field in the core keeps changing (due to change in current direction and amount) as a result of this changing magnetic field, the secondary coil (Which is not magnetized) has an e.m.f induced in it due to the changing magnetic field in the core which it is wound.
Hope that Helps!
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Through Faraday's law: http://en.wikipedia.org/wiki/Faraday%27s...
∮E◦dl = emf = -∂ϕ_B / ∂t, where ϕ_B is the magnetic flux through surface.
Since the magnetic field in the original coil is changing (due to oscillating current), so too must the magnetic field in the close by, induced coil which induces an emf, a closed loop such that the electric field does work (i.e. is non-zero).
∮E◦dl = emf = -∂ϕ_B / ∂t, where ϕ_B is the magnetic flux through surface.
Since the magnetic field in the original coil is changing (due to oscillating current), so too must the magnetic field in the close by, induced coil which induces an emf, a closed loop such that the electric field does work (i.e. is non-zero).
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