Self inductance and mutual inductance on transformers?

In summary, transformers work by mutual inductance where an alternating current in the first loop produces a changing flux, resulting in an induced emf. This alternating flux also induces an emf in the second coil, which is dependent on the number of turns. However, the flux in the first coil is affected by both the primary and secondary currents, so the relationship between the emfs in the two coils is more complex.
  • #1
inmyblood
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So I know transformers work by mutual inductance. A first loop that is connected to AC current produces an alternating B which produces a changing flux. As a result an induced Emf is formed. This Alternating B is also alternating in the second coil as well to produce same emf (if same number of loops) . right ?

and that the relation of the emf2 produced in second coil is= -N2(change in flux)/Time ... and emf1 in first coil is= N1(Change in flux)/time...

We end up with relation Emf2/N2 = Emf1/N1 .. So the emf in the first or second coil only depends on number of loops only?

BUT wait, isn't there also an Emf added in the first loop due to the AC generator itself that produces an induced emf ? doesn't that mean that the first loop has an emf from AC generator as well as another emf due to self inductance by that (AC current) ?

While the second loop only has an emf produced due to the changing flux of the first loop (mutual inductance ) and does not get the emf from the generator...

Here is a general idea of my understanding of the concept:

Generator produces-->induced emf1--->induced changing current 1 ---> induced Changing B1--->Changing in flux--> causes another induced emf2 in first loop ---> Also Change in B1 causes change in flux on loop 2---> which causes same induced emf2 in second loop.

Loop 2 has induced emf due to changing B1.

Loop1 has induced emf1 due to generator,and emf2 due to changing B1...

So how can both emf be equal even when the number of loops are the same ?
I don't know if there is something wrong in my question but i am really confused about this.
 
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  • #2
ThanksA:The transformer is an example of a linear circuit, so you can use the superposition theorem to examine what's going on. The emf in the second coil is due to two sources:the alternating current from the generator (this does not depend on N2 at all)the changing flux in the first coil (this does depend on N2).If you assume that the flux in the first coil is completely determined by the primary current, and you do the math, then you get the result that you mentioned:$$\frac{e_2}{N_2} = \frac{e_1}{N_1}$$However, this is a simplification, and in reality the flux in the first coil is affected by both the primary current and the secondary current. In that case, the result you mentioned no longer holds; the emf in the second coil depends not only on the number of turns, but also on the load connected to it.
 

1. What is self inductance?

Self inductance is the ability of a current-carrying conductor to induce a voltage in itself due to the changing magnetic field around it. It is represented by the symbol L and is measured in Henrys (H).

2. How does self inductance affect a transformer?

Self inductance plays a crucial role in the functioning of a transformer. It causes the primary and secondary coils to create a magnetic field that induces a voltage in the secondary coil, leading to the transformation of energy from one circuit to another.

3. What is mutual inductance?

Mutual inductance is the ability of two or more adjacent conductors to induce a voltage in each other due to the changing magnetic field. It is represented by the symbol M and is also measured in Henrys (H).

4. How is mutual inductance related to transformers?

Mutual inductance is the key principle behind the operation of transformers. The varying magnetic field created by the primary coil induces a voltage in the secondary coil, allowing for the transfer of energy from one circuit to another.

5. What factors affect the value of self inductance and mutual inductance on transformers?

The value of self inductance and mutual inductance depends on factors such as the number of turns in the coil, the cross-sectional area of the coil, the permeability of the core material, and the distance between the coils. These factors can be adjusted to modify the inductance value for a specific application.

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