- 8. Permeability is the ratio of flux density to magnetic field strength.
- 9. Hysteresis is defined as the lagging of magnetisation or induction flux density (B) behind the magnetizing force (H).
- 10. “The phenomenon whereby an e.m.f and hence current is induced in any conductor which is cut across or is cut by a magnetic flux is known as electromagnetic induction.
- 11. Faraday’s first law. It states that: “Whenever the magnetic flux linked with a circuit changes, an e.m.f. is always induced in it”.
“Whenever a conductor cuts magnetic flux, an e.m.f is induced in that conductor”.
- 12. Lenz’s law It states that : “In all cases of electromagnetic induction, an induced voltage will cause a current to flow in a closed circuit in such a direction that magnetic field which is caused by that current will oppose the change that produced the current”.
- 13. The e.m.f. induced by variation of flux is termed as “statically induced e.m.f.” It is further subdidvided as:
(i) Self-induced e.m.f. ;
(j) Mutually induced e.m.f.
- 14. The property of the coil due to which it opposes any increase or decrease of the current or flux through it, is known as self-inductance.
- 15. Mutual inductance is the ability of one coil (or circuit) to produce e.m.f. in a near by coil by induction when the current in the first coil changes.
- 16. Co-efficient of couplingis defined as the ratio of mutual inductance between the coils and the square root of product of self-inductance of each coil.