# Comparison between Electrical and Magnetic Circuits

Comparison of Electrical and Magnetic Circuit:

In this post we are going to see the similarities and dissimilarities between the electrical circuit and magnetic circuit. This comparison will give us a clear idea of the electrical, magnetic circuits. For your quick reference we had added the definitions magnetic circuit related terms below:

Similarities between electrical and magnetic circuits are given below

 Electric Circuit Magnetic Circuit Path traced by the current is known as electric current. Path traced by the magnetic flux is called as magnetic circuit. EMF is the driving force in the electric circuit. The unit is Volts. MMF is the driving force in the magnetic circuit. The unit is ampere turns. There is a current I in the electric circuit which is measured in amperes. There is flux φ in the magnetic circuit which is measured in the weber. The flow of electrons decides the current in conductor. The number of magnetic lines of force decides the flux. Resistance (R) oppose the flow of the current. The unit is Ohm Reluctance (S) is opposed by magnetic path to the flux. The Unit is ampere turn/weber. R = ρ. l/a. Directly proportional to l. Inversely proportional to a. Depends on nature of material. S = l/ (μ0μra). Directly proportional to l. Inversely proportional to μ = μ0μr. Inversely proportional to a The current I = EMF/ Resistance The Flux = MMF/ Reluctance The current density The flux density Kirchhoff current law and voltage law is applicable to the electric circuit. Kirchhoff mmf law and flux law is applicable to the magnetic flux.

Magnetic Circuit Terminology:

Magnetic flux:
It is defined as the amount of magnetic field produced by a magnetic
source. In other words it is the number of lines of force produced by Magnetic source. The symbol for magnetic flux is Φ.
The unit of magnetic flux is weber  (Wb).

Magnetic flux density
It is the amount of flux passing through a defined area that is perpendicular to the
direction of the flux:
Magnetic flux density = (magnetic flux) / (area)
B = Φ / A
The symbol for magnetic flux density is B.
The unit of magnetic flux density is the tesla (T)
1 T = 1Wb/m2

Magneto Motive Force (m.m.f.)
It is the cause of the presence of a magnetic flux in a magnetic circuit.

Reluctance S (or RM)
It is the magnetic resistance of a magnetic circuit to the presence of magnetic flux(Φ).
The unit of reluctance is A/Wb or H-1.

There are few dissimilarities between the two circuits which are listed below:

 Electric Circuit Magnetic Circuit In the electric circuit, the current is actually flows. ie there is movement of electrons. Due to mmf flux gets established and does not flow in the sense in which current flows. There are many materials which can be used as insulators  (air, PVC, synthetic resins etc) which current can not pass There is no magnetic insulator as flux can pass through all the materials, even through the air as well. Energy must be supplied to the electric circuit to maintain the flow of current. Energy is required to create the magnetic flux, but is not required to maintain it. The resistance and conductivity are independent of current density under constant temperature. But may change due to the temperature. The reluctance, permanence and permeability are dependent on the flux density. Electric lines of flux are not closed. They start from positive charge and end on negative charge. Magnetic lines of flux are closed lines. They flow from N pole to S pole externally while S pole to N pole internally. There is continuous consumption of electrical energy. Energy is required to create the magnetic flux and not to maintain it.

Comparison between electrical and magnetic quantities

 Electric Circuit Magnetic Circuit e.m.f. E (V) m.m.f. Fm (A) current I (A) flux Φ (Wb). resistance R (Ω) reluctance S (H−1) R= (ρl) / A S = l / μ0μrA I = E / R Φ = mmf / S

### 3 Responses

1. Navdeep says:

Very good information…frankly speaking helped a lot in my exams.

2. Arif Khan says:

Good

3. harshal R kitukale says:

it is very good information and easy to access