Whenever electric current flows through a conductor, a magnetic field will set up in the space surrounding the conductor. So, we can say that when the electron is in motion, they produce a magnetic field. Alternatively, when a magnetic field cuts a conductor, it produces a flow of electrons in the conductor. The scientist, Mr. Michael Faradays, had invented the electricity by “converting magnetism” and he had formulated the basic laws of electromagnetic induction, upon his law is based the operation of motors, generator, and transformer etc.
Now we describe how does “induced e.m.f” produce in a conductor?
Let, a stationary bar magnet is placed close to a insulated coil whose terminals are connected a sensitive Galvanometer
We can get the same result, when the bar magnet is stationary and conductor is suddenly away or towards the magnet. If a conductor AB laying within a magnetic field and a galvanometer is connected with that conductor which is shown in fig. It is found that whenever the conductor is moved up or down, a momentary deflection is produced in the galvanometer. It means that some e.m.f is induced in the conductor and the magnitude of e.m.f depends on the quickness of movement of conductor AB. It has been also observed that when the conductor AB is moved parallel to the direction of flux, so that it does not cut the flux. There will be no deflection in the galvanometer, that means there is no induced e.m.f in the coil.
From the above experiment, It has been concluded that whenever a conductor cuts or shears the magnetic flux, an e.m.f is always induced in the conductor and amount of e.m.f fully depends on the rate of cuts magnetic flux by the conductor , but not depends on the strength of magnetic flux.
Now, we describe the explanation of induced e.m.f in a coil. Let, N= No. of turns of a coil, Φ1= Initial value of magnetic flux which cuts the coil, Φ 2= Final value of flux in time t seconds. flux-linkages is meant the product of number of turns by flux linked with the coil, So, The initial flux linkages = N φ1 And final flux linkages = N φ2,
According to Faradays law of electromagnetic induction, the induced e.m.f is the rate of change of flux linkage.
Therefore, The induced e.m.f
Multiple Choice Question (MCQ) of Electronics page-17:241. Which of the following statement is true? a) The saturation voltage VCF of silicon transistor is more than germanium transistor. b) The saturation voltage VCE for germanium transistor is more than silicon transistor. c) The saturation voltage VCE for silicon transistor is same as that for germanium. d) The saturation voltage VCE for silicon transistor is lower than germanium transistor.
Multiple Choice Question (MCQ) of Electronics page-16:226. Which of the following statement is correct? a) Inner electrons are always present in the semiconductor. b) Bound electrons are always present in the semiconductor. c) Free electrons are always present in the semiconductor. d) Inner and bound electrons are always present in the semiconductor.
Multiple Choice Question (MCQ) of Electronics page-15:211. The materials whose electrical conductivity is usually less than 1 × 106 mho/m are a) Semiconductors b) Conductors c) Insulators d) Alloys
Multiple Choice Question (MCQ) of Electronics page-14:196. In which of the following device the base resistors are not added in the package but added externally? a) UJT b) CUJT c) PUT d) None of the above
Multiple Choice Question (MCQ) of Electronics page-13:181. The conduction in JEFT is always by the a) Majority carriers b) Minority carriers c) Holes d) Electrons e) Holes and electrons simultaneously