Electromagnetism

 

Electromagnetism

 

Magnet

A magnet is a material that produces a field that attracts or repels other such materials of magnetic nature.
Lodestone is a naturally occurring magnet. It attracts materials like Iron, Nickel, Cobalt etc.

North and South Poles

A magnet is always bipolar with poles named north and south poles. These two poles always exist together and can not be separated. North pole of a magnet is the side which points to Earth’s geographic north when it is freely suspended.

Like poles repel and unlike poles attract

Similar to charges, the poles attract and repel. Like poles repel while unlike poles attract each other.

Magnetic field

The region around a magnet where its magnetic influence can be experienced is called a magnetic field. The direction and strength of a magnetic field are represented by magnetic lines of force.

 

Use of Magnets: Magnets are used

·         in refrigerators.

·         in radio and stereo speakers.

·         in audio and video cassette players.

·         in children’s toys and;

·         on hard discs and floppies of computers.

Magnetic field due to a straight current carrying conductor

When current is passed through a straight current-carrying conductor, a magnetic field is produced around it. Using the iron filings, we can observe that they align themselves in concentric circles around the conductor.

Right-hand thumb rule

If a straight conductor is held in the right hand in such a way that the thumb points along the direction of the current, then the tips of the fingers or the curl of the fingers show the direction of magnetic field around it.

·        Faraday’s law of induction

    Faraday’s law of induction explains the working principle of transformers, motors, generators, and inductors. The law is named after Michael Faraday, who performed an experiment with a magnet and a coil.

      Faraday’s law of electromagnetic induction referred to as Faraday’s law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (EMF). This phenomenon is known as electromagnetic induction.

·       Fleming’s Left Hand Rule and Fleming’s Right Hand Rule

    

Whenever a current carrying conductor comes under a magnetic field, there will be a force acting on the conductor. The direction of this force can be found using Fleming’s Left Hand Rule (also known as ‘Flemings left-hand rule for motors’).

 

     Similarly if a conductor is forcefully brought under a magnetic field, there will be an induced current in that conductor. The direction of this force can be found using Fleming’s Right Hand Rule.

 

 

 

·       Fleming’s Left Hand Rule

     It is found that whenever a current carrying conductor is placed inside a magnetic field, a force acts on the conductor, in a direction perpendicular to both the directions of the current and the magnetic field.

 

      Hold out you left hand with the forefinger, second finger and thumb at the right angle to one another. If the forefinger represents the direction of the field and the second finger represents that of the current, then thumb gives the direction of the force.

 

 

·       Fleming Right Hand Rule

     As per Faraday’s law of electromagnetic induction, whenever a conductor moves inside a magnetic field, there will be an induced current in it. If this conductor gets forcefully moved inside the magnetic field, there will be a relation between the direction of applied force, magnetic field and the current. This relation among these three directions is determined by Fleming’s right-hand Rule.

 

      This rule states “Hold out the right hand with the first finger, second finger and thumb at the right angle to each other. If forefinger represents the direction of the line of force, the thumb points in the direction of motion or applied force, then second finger points in the direction of the induced current”.