Electromagnetic Induction. CLASS XII

1. KENDRIYA VIDYALAYA
SUBMITTED TO - SUBMITTED BY -
Mr. _____________ _________________
Study of phenomenon of
Electromagnetic
Induction.

2. INDEX
o CERTIFICATE
o ACKNOWLEDGEMENT
o AIM OF PROJECT
o INTRODUCTION
o THEORY
o APPLICATIONS OF EMI
o OBSERVATION
o CONCLUSION
o PRECAUTIONS
o BIBLIOGRAPHY

3. CERTIFICATE.
This is to certify that_______________, a student of class
__________has successfully completed the research on the
topic “Study of phenomenon of Electromagnetic Induction”,
under the guidance of ______________(Subject Teacher)
during the year 2019-20 in partial fulfillment of Physics
practical examination of Central Board of Secondary
Education (CBSE).
Principal. Subject Teacher.
________________ ___________________

4. ACKNOWLEDGEMENT.
I warmly acknowledge the continuous encouragement and
timely suggestions offered by our dear Principal
________________. I extend my hearty thanks for giving
me the opportunity to make use of the facilities available in
the campus to carry out the project successfully.
I am highly indebted to _______________ for the constant
supervision, providing necessary information and supporting
in completing the project. I would like to express my
gratitude towards them for their kind cooperation and
encouragement.
Finally, I extend my gratefulness to one and all who are
directly or indirectly involved in the successful completion of
this project work.
I am making this project not only for marks but to also
increase my knowledge.

6. Electro Magnet:
An electromagnet is a type of magnet in which the magnetic field is
produced by electric current. The magnetic field disappears when
the current is turned off.
Induction:
This process of generating current in a conductor by placing the
conductor in a changing magnetic field is called induction.
Electromagnetic Induction:
Electromagnetic induction is the production of a potential difference
(voltage) across a conductor when it is exposed to a varying magnetic
field.
Electromagnetic induction is when an electromagnetic field causes
molecule in another object to flow. Induction can produce electricity
(in coils), heat (in ferrous metals), or waves (in a radio transmitter).
Finally, it is refers to the phenomenon where an emf is induced when
the magnetic flux linking a conductor change.
Magnetic Flux is defined as the product of the magnetic flux
density and the area normal to the field through which the field is
passing. It is a scalar quantity and its S.I. unit is the weber (Wb).
φ = B A

7. Principle: -
Electromagnetic induction (or sometimes just induction) is a
process where a conductor placed in a changing magnetic
field (or a conductor moving through a stationary magnetic
field) causes the production of a voltage across the
conductor. This process of electromagnetic induction, in
turn, causes an electrical current -- it is said to induce the
current.

8. Invention: -
Michael Faraday is generally credited with the discovery of induction
in 1831 though it may have been anticipated by the work of
Francesco Zantedeschi in 1829. Around 1830 to 1832, Joseph
Henry made a similar discovery, but did not publish his findings
until later.
Induced e.m.f.s: -
If magnetic flux through a coil is altered then an E.m.f. will be
generated in the coil. This effect was first observed and explained by
Ampere and Faraday between 1825 and 1831. Faraday discovered
that an e.m.f. could be generated either by,
(a) moving the coil or the source of flux relative to each other or by
(b) changing the magnitude of the source of magnetic flux
in some way.
Note that the e.m.f. is only produced while the flux is
changing.
Lenz's Law: -
When an emf is generated by a change in magnetic flux according to
Faraday’s Law, the polarity of the induced emf is such that it produces a
current whose magnetic field opposes the change which produces it. The
induced magnetic field inside any loop of wire always acts to keep the
magnetic flux in the loop constant. In the examples below, if the B field is
increasing, the induced field acts in opposition to it.

9. Applications of electromagnetic Induction -
Electrical Generator: -
The EMF generated by Faraday's law of induction due to relative movement
of a circuit and a magnetic field is the phenomenon underlying electrical
generators. When a permanent magnet is moved relative to a conductor, or
vice versa, an electromotive force is created. If the wire is connected through
an electrical load, current will flow, and thus electrical energy is generated,
converting the mechanical energy of motion to electrical energy
Electrical transformer: -
The EMF predicted by Faraday's law is also responsible for electrical
transformers. When the electric current in a loop of wire changes, the
changing current creates a changing magnetic field. A second wire in reach of
this magnetic field will experience this change in magnetic field as a change in
its coupled magnetic flux, d ΦB / d t. Therefore, an electromotive force is set
up in the second loop called the induced EMF or transformer EMF. If the
two ends of this loop are connected through an electrical load, current will
flow.

10. Faraday’s Experiment: -
✓ One of the scientists Faraday performed series of experiments
and based on the results he gave law on induction.
✓ He introduced the phenomenon of electromagnetic induction.
✓ Induction means to induce or to generate something.
✓ Electromagnetic Induction means production of electric
current due to magnetic field.
✓ Magnetic field is capable of producing current in a conductor
✓ Faraday took a coil and attached a galvanometer to it.
✓ As there is no battery attached therefore there is no source of
current.
✓ He brought the magnet near the coil.
✓ When the magnet is moved towards the coil galvanometer
showed deflection.
✓ Galvanometer even showed the deflection in the opposite
direction when the magnet is taken away from the coil.
✓ When magnet was not moved there was no deflection in the
galvanometer.
✓ This show current is related to magnet.
✓ Faster the magnet is moved the more is the deflection in the
galvanometer. This showed more and more current flows if the
magnet is moved very fast.
✓ Same effect was observed if the coil is moved and the magnet
was not moved.

11. Materials Required: -
Magnetic bar, a galvanometer, coil and connecting wires.
Procedure: -
1. Take a coil of wire having a large number of turns.
2. Connect the end of the coil to a galvanometer.
3. Take a strong bar magnet and move its north pole into the coil
and observe the changes in the galvanometer needle.
4. Repeat earlier step with the south pole of the bar magnet.
5. Now repeat the procedure with the coil having a different number
of turns and the variation in the deflection of the galvanometer
needle.
Observations: -
1. When we move the magnet in or out of the coil, the needle of
galvanometer gets deflected in different directions.
2. When we insert the north pole (N) of bar magnet into the coil,
the deflection is towards right.
3. When we insert the south pole (S) of bar magnet into the coil, the
deflection is towards left.
4. When we move the bar magnet in or out of the coil with varying
speed, the speed of deflection changes accordingly.

12. 5. As we increase the number of turns in the coil, the deflection
increases.
6. Relative motion between magnet and coil induced electric current
in the coil.

15. Result: -
1. The deflection of galvanometer needle indicates the presence of
current in the coil.
2. The direction of deflection gives the direction of flow of current.
3. The speed of deflection gives the rate at which the current is
induced.
4. The deflection in galvanometer changes with the change in
number of turns in the coil - more the number of turns in the coil
greater is the deflection.
From this experiment, Faraday concluded that whenever there is
relative motion between a conductor and a magnetic field, the flux
linkage with a coil changes and this change in flux induces a voltage
across a coil.

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