Electromagnetic Induction: Overview, Questions, Preparation

Electromagnetism is one of the fundamental interactions in nature. Electromagnetism is the force that causes electrically charged particles to interact; the areas in which this happens are called electromagnetic fields. For example, electromagnetism is responsible for the result of intermolecular forces between individual molecules. It is the force that holds electrons and protons together.

Electromagnetism is the generation of a magnetic field by the current in a conductor. So, it unites both electricity and magnetism. A changing electric field produces a magnetic field. A changing magnetic field produces an electric field. When propagated outward at the speed of light, these two fields support each other. It leads to the creation of electromagnetic waves, radio waves, and X-rays. 

Example

If a current-carrying wire is inserted through a sheet of paper in the perpendicular direction, iron filings placed on the paper surface arrange themselves along the magnetic lines of force in concentric rings.

• The resultant magnetic field is strong when close to the conductor and becomes weaker with increasing distance from the conductor. 
• When the direction of current is left to right, the lines are in a clockwise direction. When the current is right to left, the lines are in a counterclockwise direction.
• The iron filings show the pattern but not the direction of the magnetic field. This observation leads to the right-hand rule. 

The right-hand rule reflects Oersted's discovery. It is for determining the direction of a field created by a current in a wire.                

• When you place the thumb of your right hand in the direction of the electric current inside the wire, your fingers curl in the direction of the magnetic field. 
• The direction of the magnetic field changes due to the changes in the direction of the electric current.
• The strength of the magnetic field around the current-carrying wire is related to the size of the current in the wire. As the current increases, the magnetic field increases.
• Thus the current-carrying wire produces a magnetic field whose strength depends on the amount of the current flowing, and the direction depends on the direction of current flow. This led to the development of electromagnets.

 Many types of user devices such as tape recorders, electric motors, speakers, solenoids, and relays form the basis of electromagnetism.

The television uses the solenoid to generate the magnetic fields needed. The synchrotron uses a combination of both to generate high magnetic fields.

The magneto-optical disk uses an electromagnet and laser beams to read and write data on a magnetic surface.

For this class, electromagnetism is expressed as the magnetic field due to the current-carrying conductor, circular loop, and solenoid. The right-hand rule and the force on a current-carrying conductor in a magnetic field are also covered. The topic has a weightage of around 5 marks.

For class 12, we get to see the magnetic field due to the current element, Biot-Savart law, and circular current loop. Magnetic field lines, electromagnets, electromagnetic induction, and the details of solenoid and toroid are also covered. The weightage of the topic is 5%.

1. What is the formula of magnetic field strength for electromagnets?

A: