Mutual Inductance: Coil 1 Excited, Coil 2 Open Circuited

In summary: N1 and N2 are both needed for the number of turns in the B=U0NI/L. N1 is needed for the AB circuit and N2 is needed for the BC circuit. In the DRIVE CIRCUIT, only N1 or N2 can be chosen depending on which coil is being driven.
  • #1
ezcheez
5
0
I have a very basic question regarding mutual inductance.

Consider a basic square loop with two coils wound on opposite sides from each other, with coil one excited while coil two si left open circuited. The total flux linking coil 1 is

Φ11 = Φl121

where

Φ11 is the total flux linking coil 1
Φl1 is the leakage flux and
Φ21 is the mutual flux linking both coils

My question is why there is mutual flux if the second coil is open-circuited, in other words, why is Φ21 non-zero? I would expect flux through the iron core due to coil one but how/why does coil two contribute to this flux?
 
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  • #2
Here [tex]\phi_{l1}[/tex] is the leakage flux i.e., the flux which is linking only with first winding and not with second winding and is due to imperfect coupling. The flux [tex]\phi_{l21}[/tex] is the one which interlinks with both windings. Since [tex]\phi_{l21}[/tex] has nothing to do with the second coil's open or short circuit conditions it won't be zero. You may refer the Wikipedia's page below
http://en.wikipedia.org/wiki/Leakage_inductance
 
  • #3
Let me take step back and ask this question:

What would happen to the flux in the magnetic core if the second coil is removed? Does only the leakage flux remain, or would some flux still flow through the whole core?
 
  • #4
In fact when the second coil is open circuited, the first coil behaves as if it is the only inductor present in the core. So even if the second coil is removed, the flux going through the core [tex]\phi_{l21}[/tex] will be the same.
 
  • #5
That helps a great deal. I am going to ponder that for a little while...
 
  • #6
n.karthick said:
In fact when the second coil is open circuited, the first coil behaves as if it is the only inductor present in the core. So even if the second coil is removed, the flux going through the core [tex]\phi_{l21}[/tex] will be the same.
Hey Karthick,
This is different you have been discussing,Should I use N1+N2 for the no.of turns in the B=U0NI/L where both the coils are one over the other , but one is NOT Connected?
Or should I take only N1 or N2 which ever coil is driven by DRIVE CIRCUIT.

Regards
Geetika
 

1. What is mutual inductance?

Mutual inductance is a phenomenon in which a changing current in one circuit induces a voltage in another nearby circuit. This is due to the magnetic field generated by the changing current, which can pass through the nearby circuit and induce a current in it.

2. How does mutual inductance work?

In mutual inductance, the changing current in one circuit creates a changing magnetic field around it. This magnetic field can then pass through the nearby circuit and induce a voltage according to Faraday's law of induction. This voltage can then drive a current in the nearby circuit.

3. What is the significance of coil 1 being excited and coil 2 being open circuited in mutual inductance?

In this scenario, the current in coil 1 is changing and creating a magnetic field, while the circuit in coil 2 is open, meaning there is no closed loop for current to flow. This allows for the magnetic field to pass through the nearby circuit and induce a voltage, demonstrating the principle of mutual inductance.

4. How is mutual inductance measured?

Mutual inductance can be measured by connecting a circuit with a known current and measuring the voltage induced in the nearby circuit. The ratio of the induced voltage to the current in the first circuit is equal to the mutual inductance between the two circuits.

5. What are some real-world applications of mutual inductance?

Mutual inductance is used in many electronic devices, such as transformers, motors, and generators. It also plays a crucial role in wireless charging technology, where a changing magnetic field is used to induce a current in a nearby device. Inductive coupling is also used in communication systems, such as RFID tags and wireless power transfer systems.

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