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Difference Between Induced EMF and Current

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Last updated date: 27th Feb 2024
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Entering the World of Electrodynamics

As per Merriam Webster, Electrodynamics can be defined as a branch of physics that deals with the effects arising from the interactions of electric currents with magnets, with other currents, or with themselves. As a branch of physics, the two most basic concepts that it deals with induced emf and current. Faraday’s laws govern the principle of induced electromotive force(emf). They reiterate the fact that while current is only induced in closed loops or circuits where emf and current cannot both be the same, emf is induced whenever there is a change in magnetic flux.

What is Induced Electromotive Force(Induced EMF)?

Because of changes in the magnetic flux passing through a coil, a potential difference is created in the coil. To put it another way, it is claimed that the flux connecting with a wire or coil changes to produce electromotive force, or emf.


There are two ways to create electromotive forces:


  • The first method entails positioning an electric conductor in a fluctuating magnetic field.

  • The second method entails positioning a conductor that is constantly moving in a magnetic field that is static in nature.


Alternatively, When the magnetic flux connecting the conductor or coil changes, electromotive force, or EMF, is known to be induced.


Formula for Induced EMF:

1. Induced Emf in a Rod

$e=BLv$

Where, e= induced emf in a rod,

B= magnitude of magnetic field

L= length of the rod

v = speed of the moving object in relation to magnetic field


From the above equation, it can be inferred that induced emf is directly proportional to magnitude of magnetic field, length of the conducting rod and speed of the moving object in relation to magnetic field


2. Induced Emf Obeying Lenz’s Law: 

According to Lenz's law, a current will flow through the loop in response to an induced electromotive force with a different polarity in order to maintain the original magnetic flux there while the current is flowing. Alternatively, when magnetic flux linking a conductor charges, induced emf is generated. 

$e=-N\frac{\mathrm{d} \phi }{\mathrm{d} t}$


Where, e= induced emf

N= number of turns

Φ= magnetic flux

t= time


Electric Current: Greatest Invention of Humanity

Current is the movement of electrical charge in a closed circuit through a conducting body. Its SI unit is the ampere, represented by the letter A, and it is expressed in Coulombs per second. It demonstrates three unique characteristics:


  • Heating Effect: When current travels through a conductor, heat is created. This heating effect is illustrated by:

$H=I^{2}RT$


  • Magnetic Effect: When current flows through a conductor, a magnetic field is created. This is comparable to what happens when we place a compass near a wire carrying a lot of current and the needle begins to sway.


  • Chemical Reaction: When current is transmitted through a solution, a chemical reaction is stated to take place, further dissolving the solution into ions.


Relationship Between Induced Electromotive Force and Current: 

During a number of tests conducted by Faraday, he identified the connection between induced EMF and current. He linked a galvanometer in series with a cylindrical coil composed of insulated copper wire. He then pushed a bar magnet up and down while orienting it so that the north pole was towards the coil. This produced the following findings that demonstrated the relationship between induced EMF and current:


  • Whenever there is a relative motion between coil and magnet, the galvanometer shows a deflection testifying the idea that there is an induced emf in the coil.

  • As the magnet's position changes, so does the direction of the current flow.

  • The deflection is a function of the magnet's speed; in other words, the faster the magnet moves, the greater deflection it experiences, and vice versa.


Induced emf in a coil


Induced emf in a coil


Faraday’s Laws

According to Faraday's First Law, an electromagnetic field (EMF) is created when the magnetic flux across a coil gradually changes. The coil of the magnetic loop can be moved, rotated, the magnet can be moved near or far from the coil, and the position of the coil within the magnetic field can all be altered to alter the magnetic field's strength.


Faraday's Second Law: Faraday's law, which demonstrates the relationship between current and induced EMF, was built on the connection between induced EMF and current. According to Faraday's second law, the induced EMF is proportional to the flux's rate of change.


$e=-N\frac{\mathrm{d} \phi }{\mathrm{d} t}$


Where, e= induced emf

N= number of turns

Φ= magnetic flux

t= time


Differentiate Between Induced EMF and Current: 

S.No

Category

Induced Electromotive Force (EMF)

Current


Definition

It is the shift in potential difference brought on by a coil's changing magnetic flux. 

It is the movement of ions or electrons within a sealed circuit.


Formula

.$e=-N\frac{\mathrm{d} \phi }{\mathrm{d} t}$

Where, e= induced emf

  N= number of turns

 Φ= magnetic flux

  t= time


$I=V/R$

Where, I= current in the closed circuit

V= potential difference applied

R= resistance in the circuit


Point of Measurement

Since emf is the potential difference, we measure energy.

The rate of electron passing in a conductor is known as electric current. So we measure the rate of flow of electrons in the circuit.


SI Unit

Since it is nothing but potential difference, its SI unit is Volt(V).

Its SI unit, the ampere, is represented by the letter "A".


Uses

Induced emf can be utilized in induction cooking, solar powered technologies, electric generators, etc.

Current is used to run electrical devices that we can see in everyday life like refrigerators, air conditioners, fans, LED bulbs, etc.


Summary

The fundamental aspects of both concepts were perfectly portrayed in this article on what is induced emf and current as well as to differentiate between induced emf and current. Through Faraday's experiments, the relationship between induced emf and current was presented. A brief discussion of two of his experiments has been provided, illustrating the relationship between induced emf and current. The new concept of induced emf produced when  magnetic flux linking a conductor charges was introduced. The article also explored the origin of the phrase electromagnetic induction, which refers to both current and induced emf.

FAQs on Difference Between Induced EMF and Current

1. What is induced EMF and current?

The concept of induced emf is of utmost significance to understand the inner processes of electrodynamics. In an induced emf, voltage will be generated if the magnetic flux through a coil is altered. The induced emf is the name given to this voltage. SI unit of induced electromotive force is Volt(V). On the other hand, Current is the rate of flow of electrons in a circuit. The Ampere is the SI unit of electric current.

2. How is EMF induced dynamically?

Electromotive force is induced through two ways i.e., statically induced emf and dynamically induced emf. In a dynamically induced emf, the conductor or magnetic field is kept moving while the other is kept stationary. For instance, the conductor is stationary when the magnetic field is maintained in motion. The electromotive force is induced by either of the two processes, and the conductor is able to readily cross the magnetic field. An important point is the fact that when magnetic flux linking a conductor charges, induced emf is generated.

3. What is mutual induction?

Electromotive force (emf), which is a phenomenon, is created in the secondary coil whenever the primary coil's current changes. The change in current (dI/dt) in the main coil has a direct proportional relationship with the emf (e) generated in the secondary coil. The materials of the coil wires affect the mutual inductance between them.

4. What are various applications of Faraday’s Law?

Faraday’s law has a plethora of applications in this world. Faraday’s law is utilized in the working of transformers and induction cookers. The velocity of the fluids is measured by applying an electromotive force to an electromagnetic flowmeter. Faraday's law, which asserts that a change in the magnetic field causes a change in the electric field, is the basis for Maxwell's equation too.