These are the following laws, which are known as Faraday’s law of electromagnetic induction.
1st law
According to the first law of electromagnetic induction, “whenever the flux linking with a coil or circuit changes, an e.m.f. is induced in it”. This linkage can be obtained either by rotating the conductor in the magnetic field or by rotating the magnetic field keeping the conductor stationary.
2nd Law
According to the second law of electromagnetic induction, “the magnitude of the induced e.m.f. in a coil is directly proportional to the rate of change of flux linkage”. the rate of change of flux linkage.
Let there be a coil having ‘N’ turns. the initial flux being Φ1 and the final flux value after time ‘t’ is Φ2.
Magnetism and Electromagnetism
The net change in flux
and the rate of change of flux linkage
Now according to Faradays laws of Electromagnetic induction. The e.m.f. rate of change of flux linkage
where k is the constant of proportionality and here being unity
Induced e.m.f. = rate of change of flux x No. of conductors and it can be otherwise stated as
What do you understand by the phenomenon of Electromagnetic Induction?
Whenever electric current flows through a conductor magnetic lines of force are produced around the conductor, the converse is also equally true, that the electricity can be induced/generated by changing the magnetic flux linking the conductor. So “the process by which an e.m.f. and hence current is induced/generated in a conductor whenever there is a change in the magnetic flux linking the conductor, is called the electromagnetic induction”.
Lenz’s law
The e.m.f. induced, according to the Faradays laws of electromagnetic induction, has got only the strength of the magnitude and is silent over the direction. The direction was stated by Lenz’s laws in 1835.
According to lenz’s law, the direction Of the induced e.m.f. because of the electromagnetic induction is such a way as to oppose the cause which is responsible for the production of this e.m.f.
The equation can be given as
The minus sign indicates the direction of the induced e.m.f. i.e. opposing.
Fleming’s right hand rule.
This rule is applied to find out the direction of the induced e.m.f. in a conductor. According to this law, stretch your right hand in such a way as to keep the thumb, middle finger, and forefinger at right angle to each other. If the thumb indicates the direction of motion and the forefinger indicates direction of the magnetic flux, then the middle finger will indicate the direction of the induced e.m.f. in the conductor as shown in Fig. 11.26.
The e.m.f. can be induced by the following ways:
(i) Dynamically induced e.m.f. (ii) Statically induced e.m.f.
Example. A magnetic flux of 0.004 Wb is made to link a coil having 500 turns in 0.1 sec. Find the average induced e.m.f.
Solution. The induced e.m.f. rate of change of flux linkage.
Here N = 500, t = 0.1 sec and flux = 0.004 Wb
