Electro-magnetism, Faraday’s & Lenz’s laws, induced EMF and its uses

By Mona Kumari|Updated : June 9th, 2021

In This chapter we will learn about Electromagnetism, Faraday’s & Lenz’s laws, induced EMF and its uses.

 

                                 

 

      

In This chapter we will learn about Electro-magnetism, Faraday’s & Lenz’s laws, induced EMF and its uses.

An electric circuit is an interconnection of electrical elements.

A simple electric circuit is shown below with a connection of the battery and a lamp.

byjusexamprep

Circuit → closed

The network → may or may not be close

Ohm’s Law: It states that at a constant temperature, the current density is directly proportional to the electric field intensity.

J = current density

E = electric field intensity

byjusexamprep

.byjusexamprep

byjusexamprep

   Inductor:

The inductor is a circuit element that opposes the change in current.

The voltage across the inductor is proportional to the derivative of the current with respect to time.

V=L di/dt

→ It stores the energy in the form of the magnetic field.

. Faraday Law of electromagnetic induction:

  1. If a flux linking a coil varies as a function of time then an emf is induced between its terminals (statically induced emf)

or

when a conductor cuts the magnetic line of force, an emf is induced in the conductor (dynamically induced emf.

byjusexamprep

 

. Types of inductor:

  1. A) Linear inductor: When the inductance of the inductor is independent of the current magnitude then the inductor is called a linear inductor. For eg: air-cored inductor
  2. B) Non – Linear inductor: when the inductance of the inductor depends on a current magnitude, then the inductor is called as non – linear inductor. For eg: iron cored inductor.

byjusexamprep

 .ELECTROMAGNETIC INDUCTION

When the magnetic flux linking a conductor (or coil) changes, an e.m.f is induced in the conductor. If the conductor forms the complete path, a current will flow in it. This phenomenon is known as electromagnetic induction.

Flux linkage: The product of a number of turns (N) of the coil and the magnetic flux linking the coil is called flux linkages.

Flux linkages

.   Faraday’s Laws of Electromagnetic Induction:

When the magnetic flux linking a conductor (or coil) changes, an e.m.f is induced in the conductor. If the conductor forms the complete path, a current will flow in it. This phenomenon is known as electromagnetic induction.

Flux linkage: The product of number of turns (N) of the coil and the magnetic flux linking the coil is called as flux linkages.

. Faraday’s First Law:

Faraday’s first law states that when the flux linking with the coil or circuit changes an emf is induced in it or whenever the magnetic flux is cut by the conductor an emf is induced in the conductor.

. Faraday’s Second Law:

Faraday’s Second law states that the magnitude of emf induced is directly proportional to the rate of change of flux linking the coil.

i.e. induced emf ∞ N (d∅)/dt

where N (d∅)/dt is the product of the number of turns and rate of change of linking flux is known as the rate of change of flux linkages.

. Lenz’s Law:

Lenz’s law states that the direction of induced emf is such that the current produced by it sets up a magnetic field opposing the motion or change producing it.

E= - N (d∅)/dt

.INDUCED EMF

When the magnetic flux linking a conductor changes, an e.m.f is induced in it. This change in flux can be induced by changing the linking flux in two ways:

  • By increasing or decreasing the magnitude of the current producing the linking flux. In this case, there is no motion of the conductor or of the coil relative to the field and, therefore, emf induced in this way is known as statically induced emf.
  • By moving a conductor in a uniform magnetic field and emf produced in this way is known as dynamically induced emf.

The direction of this induced emf is given by Fleming’s right-hand rule.

Fleming Right-hand rule: If the thumb, forefinger and middle finger of the right hand are held mutually perpendicular to each other forefinger pointing into the direction of the field and thumb in the direction of motion then the middle finger will point in the direction of the induced emf.

Candidates can practice 150+ Mock Tests with BYJU'S Exam Prep Test Series for exams like GATE, ESE, NIELIT from the following link:

Click Here to Avail Electronics Engineering Test Series (150+ Mock Tests)

Get unlimited access to 24+ structured Live Courses all 150+ mock tests to boost your GATE 2021 Preparation with Online Classroom Program:

Click here to avail Online Classroom Program for Electronics Engineering

Thanks

Sahi Prep Hai To Life Set Hai.

 
Download BYJU'S Exam Prep, Best gate exam app for Preparation

Comments

write a comment

Follow us for latest updates