## Electromagnetic Induction

# Inductance

An inductor is a device for storing energy in a magnetic field.an inductor is generally called as inductance.

**Self induction :** The phenomena of production of induced emf in a circuit due to change in current flowing in its own, is called self – induction.

Coefficient of self induction **(Φ****) = LI**

**Mutual induction**: The phenomena of production of induced emf in a circuit due to the change in magnetic flux in its neighboring circuit is called mutual induction.

Coefficient of mutual induction **(****Φ****) = MI**

### View the Topic in this video From 25:08 To 59:21

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1. By Faraday's second law, induced emf e = -N\frac{d \phi}{dt}, which gives e = -L \frac{di}{dt}; if \frac{di}{dt} = 1 amp/sec then |e| = L.

2. According to Faraday's second law emf induce in secondary is e_{2} = - N_{2} \frac{d \phi_{2}}{dt}; e_{2} = -M \frac{di_{1}}{dt}

3. Relation between M, L_{1} and L_{2} : For two magnetically coupled coils M = k\sqrt{L_{1}L_{2}}

4. Series: If two coils of self-inductances L_{1} and L_{2} having mutual inductance *M* are in series and are far each other, so that the mutual induction between them is negligible, then net self inductance L_{s} = L_{1} + L_{2}

5. Parallel : If two coils of self-inductances L_{1} and L_{2} having mutual inductance are connected in parallel and are far from each other, then net inductance L is \frac{1}{L_{P}} = \frac{1}{L_{1}} + \frac{1}{L_{2}}