The similarity between electric and magnetic circuit is given in table 1
Table 1
SL No. |
Electric Circuit |
Magnetic Circuit |
|---|---|---|
| 1 | Conductivity \(\sigma\) | Permeability \(\mu\) |
| 2 | Intensity of electric field E | Intensity of magnetic field H |
| 3 | Electro motive force (emf) potential difference or voltage | Magneto motive force (mmf) magnetic voltage |
| 4 | Current \(I=\int{\vec{J.}\vec{ds}}\) | Magnetic flux \(\mathrm{\Phi}=\int{\vec{B.}\vec{ds}}\) |
| 5 | Current density J \(J=\frac{1}{S}=\sigma E\) | Flux density \(B=\frac{\mathrm{\Phi}}{S}=\mu H\) |
| 6 | Resistance | Reluctance |
| 7 | Conductance | Permeance |
| 8 | Ohm’s law \(R=\frac{V}{I}=\frac{1}{\sigma S}\) | Ohm’s law \(Ӄ=l\mu S\) |
| 9 | Kirchhoff’s laws \(\sum I=0\) and \(\sum V-\sum I R=0\) | Kirchhoff’s laws \(\sum\mathrm{\Phi}=0\) and \(Ӄ-ӃΦ=0\) |
Some dissimilarity between electric and magnetic circuits are given below:
- Unlike an electric circuit when current actually flows an electrical conductor, magnetic flux in a magnetic circuit does not flow through a magnetic material.
- In an electric circuit energy must the supplied to maintain the flow of current and this energy is dissipated as heat produced in the resistance of the circuit. In a magnetic circuit once the magnetic flux leakage is set up, it does not require further supply of flux to maintain the same since energy is stored in the magnetic field.
- Conductivity \sigma is independent on the current density J in an electric circuit where as permeability \mu depends on flux density B in a magnetic circuit. This is due to the fact that ferromagnetic materials are nonlinear and these are mostly used in most practical magnetic circuits.
- Magnetic flux can flow through a small cut in an iron ring i.e., the flux flows through air gap. In case of electric circuit, current cannot flow through any air gap or through discontinuity of a conductor.
Fig.23