Faraday’s law and transformer emf

FARADAY’S LAW AND TRANSFORMER EMF

• Name: Mukhamadbobur Kurbonov
• Dept. of Mechatronics Engineering
• Student id: 2019116303

MAXWELL’S EQUATIONS

• Faraday’s Law of Induction
• Transformers

• MAXWELL’S EQUATIONS

• Maxwell’s equations are not mere theoretical speculations; rather, each was developed to explain the results of laboratory experiments.
• What is specially remarkable about Maxwell’s equation is that they are entirely consistent with the special theory of relativity, in contrast to Newton’s laws for mechanics which require major changes for motion at speed close to speed of light, Maxwell’s equations remain the same for all observers, no matter what their relative speeds. In fact Einstein’s discovery of relativity grew directly from his thinking about the laws of electromagnetism and Maxwell’s equations.

• 1. Gauss’s Law for Electricity

• 2. Gauss’s Law for Magnetism

• 3. Faraday’s Law of Induction
• The electric effect of changing magnetic field

• MAXWELL’S EQUATIONS

• 4. Ampere’s Law (as extended by Maxwell)
• The magnetic effect of a current or a changing electric field

• where as

• In 1831, Michael Faraday, an English physicist gave one of the most basic laws of electromagnetism called Faraday's law of electromagnetic induction. This law explains the working principle of most of the electrical motors, generators, electrical transformers and inductors. This law shows the relationship between electric circuit and magnetic field. Faraday performs an experiment with a magnet and coil. During this experiment, he found how emf is induced in the coil when flux linked with it changes.

• FARADAY’S EXPERIMENT

• In this experiment, Faraday takes a magnet and a coil and connects a galvanometer across the coil. At starting, the magnet is at rest, so there is no deflection in the galvanometer i.e needle of galvanometer is at the center or zero position. When the magnet is moved towards the coil, the needle of galvanometer deflects in one direction.

Position of magnet	Deflection in galvanometer
Magnet at rest	No deflection in galvanometer
Magnet moves towards the coil	Deflection in galvanometer in one direction
Magnet is held stationary at same position (near the coil)	No deflection in galvanometer
Magnet moves away from the coil	Deflection in galvanometer but in opposite direction
Magnet is held stationary at same position (away from the coil)	No deflection in galvanometer

• FARADAY’S EXPERIMENT

• From this experiment, Faraday concluded that whenever there is relative motion between conductor and a magnetic field, the flux linkage with a coil changes and this change in flux induces a voltage across a coil. Michael Faraday formulated two laws on the basis of above experiments. These laws are called Faraday's laws of electromagnetic induction.

• Faraday's First Law
• Any change in the magnetic field of a coil of wire will cause an emf to be induced in the coil. This emf induced is called induced emf and if the conductor circuit is closed, the current will also circulate through the circuit and this current is called induced current. Method to change magnetic field:
• By moving a magnet towards or away from the coil
• By moving the coil into or out of the magnetic field.
• By changing the area of a coil placed in the magnetic field
• By rotating the coil relative to the magnet.

• FARADAY’S LAW OF ELECTROMAGNETIC INDUCTION

• Faraday's Second Law
• It states that the magnitude of emf induced in the coil is equal to the rate of change of flux that linkages with the coil. The flux linkage of the coil is the product of number of turns in the coil and flux associated with the coil.

• The negative sign used in Faraday's law of electromagnetic induction, indicates that the induced emf ( ε ) and the change in magnetic flux ( δΦB ) have opposite signs.

FARADAY’S LAW OF INDUCTION

• To induce an emf we can change,
• the magnitude of B
• the area enclosed by the loop
• the angle between B and the normal to the area
• any combination of the above
• over time.

ELECTRIC GUITAR

• To Amplifier

• Pickup Coil

• Magnet

• Guitar String

• N

• S

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THANK YOU