# Relation between MMF and Flux of a Transformer

A transformer is a two port device which transforms energy by inductive coupling between its winding circuit.It has a core that transforms current MMF from its primary circuit to its secondary circuit. The primary parameters are I1, E1, V1 and the secondary parameters are I2, E2, V2. A transformers are constructed in two types core type and shell type.more over transformer are of two uses one for step down voltage i.e from high voltage to low voltage and another is step up voltage i.e from loww voltages to high voltages.

**Relation between MMF and Flux of a Transformer**** :-**

**To know about relation between MMF and Flux of a transformer we have to know what is transformer,MMF and Flux.**

**TRANSFORMER:**

The transformer is an electrical device which transfers energy by inductive coupling between its winding circuit.

**MAGNETIC FLUX:**

Magnetic flux is defined as the product of the average mangetic field times the perpendicular area.

**MMF(Magnetomotiveforce):**

Magnetomotiveforce is defined as the product of current flowing through the wire and the numbers of windings.

**INDUCTION LAW:
**There are basically two principles of transformer,

- Magnetic field is produced by electric current.
- Change in magnetic field within a coil of wire induces a voltage across end of of the coil

When current passes through primary coil it creates a magnetic field and that magnetic flux passes through both primary and secondary coils.

Now from faraday’s law of induction,

**V _{S}=E_{S}=N_{S}d fi/dt**

Where V_{S}=E_{S}=instantaneous voltage

N_{S} is number of turns in secondary coil

dfi/dt is derivative of the magnetic flux through one turn of the coil

**RELATION BETWEEN MMF AND FLUX:**

**F _{M}=H.L**

_{e }H=Magnetic field strenght

L

_{e}=effective magnetic path length

Again F

_{M}=I.N

I=current flowing through wires

N=numbers of turns of coil

fi=V.T/N

V=voltage developed

**fi=F _{M}/R_{M}**

R_{m}=Reluctance

**fi=2W/F _{M}**

where,W is Field energy in joules.

**IMPORTANT QUESTIONS:**

1. What is transformer?

Ans. The transformer is an electrical device which transfers energy by inductive coupling between its winding circuit.

2. What is magnetic flux?

Ans. Magnetic flux is defined as the product of the average magnetic field times the perpendicular area.

**F _{M}=H.L_{e}**

H=Magnetic field strenght

L_{e}=effective magnetic path length

Again F_{M}=I.N

I=current flowing through wires

N=numbers of turns of coil

3. What is the relationship between mmf and flux of a transformer?

Ans **F _{M}=H.L_{e}**

H=Magnetic field strenght

L_{e}=effective magnetic path length

Again F_{M}=I.N

I=current flowing through wires

N=numbers of turns of coil

**fi=V.T/N
**V=voltage developed

fi=F

_{M}/R

_{M }R

_{m}=Reluctance

**fi=2W/F**where,W is Field energy in joules

_{M }4. What is the expression for induction law for transformer?

Ans. **V _{S}=E_{S}=N_{S}d fi/dt**Where V

_{S}=E

_{S}=instantaneous voltage

N

_{S}is number of turns in secondary coil

5. What are the working principle of transformer?

Ans. There are basically two principles of transformer,

- Magnetic field is produced by electric current.
- Change in magnetic field within a coil of wire induces a voltage across end of of the coil

**For more questions on Transformer one can refer to the below links:-
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**For more topics on Transformer one can refer to the following:-
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This article is about Relation between MMF and flux of transformer.A transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. A varying current in the primary winding creates a varying magnetic flux in the transformer’s core and thus a varying magnetic flux through the secondary winding.