Moving Charges and Magnetism Class 12 Physics Chapter 4 Notes, MCQ, PDF, Formulas


MOVING CHARGES AND MAGNETISM – CBSE moving charges and magnetism class 12 notes and a detailed description of the chapter and the definitions are provided to you. Also, the summary is followed by some extra questions from the chapter. There are answers for moving charges and magnetism notes provided after the summary for your easy revision. MOVING CHARGES AND MAGNETISM – CBSE questions have also been solved by us.

Class 12 Physics Chapter 4 Moving Charges and Magnetism Notes 

Here, we have tried to give you a simple summary with some extra questions of Class 12 Physics Chapter 4 –MOVING CHARGES AND MAGNETISM along with moving charges and magnetism class 12 notes. After that, you can also go through some extra questions in chapter 4. 

In our childhood, we all might have experienced iron nails getting attracted to a magnet. We have also witnessed or heard current-carrying copper wire wound around iron acting as a magnet in a science project. At that time all of that seemed magical, although it is all science. It is due to magnetism.

Magnetism is a phenomenon due to which moving charges (or magnets) attract ferromagnetic objects and repel diamagnetic objects.

Also Read : Indigo Summary Class 12

Oersted’s Experiment

A magnetic field is produced in the surrounding of any current-carrying conductor.
The direction of this magnetic field can be obtained by Ampere’s swimming rule.

  • SI unit of the magnetic field is Wm-2 or T (Telsa).
  • The strength of the magnetic field is called one tesla, if a charge of one coulomb, when moving with a velocity of 1 ms-1 along a direction perpendicular to the direction of the magnetic field experiences a force of one newton.
  • 1 tesla (T) = 1 weber metre-2 (Wbm-2) = 1 newton ampere-1 metre-1 (NA-1 m -1)
  • CGS units of the magnetic field are called gauss or oersted. 1 gauss = 10-4 tesla.

Magnetic line of force

If a right-handed corkscrew is imagined to be rotated in such a direction that tip of the screw points in the direction of the current, then direction of rotation of the thumb gives the direction of magnetic line of force.

  • The conventional sign for a magnetic field coming out of the plane and normal to it is a dot i.e., The magnetic field perpendicular to the plane in the downward action is denoted by ®.

Ampere’s Swimming Rule

If a man is swimming along the wire in the direction of current his face turned towards the
needle, so that the current enters through his feet, then the north pole of the magnetic needle will be deflected towards his left hand.

Magnetic field

  • The magnetic field is an effect around a permanent magnet or a moving charge due to which ferromagnetic objects like some metals get attracted, and diamagnetic substances get repelled, when placed in the magnetic field.
  • A charge in motion generates a magnetic field, just like a charge at rest generates an electric field
  • The magnetic field at a point r is denoted by B(r). It is a vector quantity, just like electric field E(r)
  • The magnetic field can change with both distance and time
  • Magnetic field due to more than one source can be obtained by vectorial addition of all sources. This is the principle of superposition. This characteristic is also similar to the electric field.


If you are studying in Class 12 you can also check Class 12 NCERT Physics Solutions from here along with moving charges and magnetism class 12 . This will help you to know the solutions for all subjects covered in moving charges and magnetism class 12 notes. You can click on the subject wise link to get the same. Class 12 Chapter-wise, detailed solutions to the questions of the NCERT textbooks are provided with the objective of helping you compare their answers with the sample answers.

Read more: The Last Lesson – Class 12 English Flamingo Summary with Extra Questions


In this section, we will let you know some of the important questions and answers that might help you in the exam based on moving charges and magnetism class 12 notes. 

1. What is moving charge and magnetism?

Answer: Moving charges or flow of charge causes magnetism. Moving Charges and Magnetism explain that magnetic fields further exert forces on the flow of charge, which in turn, exerts a force on other magnets. Such a phenomenon takes place because of the presence of consistent moving charges.

2. What is an example of a moving charge?

Answer: Magnetic force can cause a charged particle to move in a circular or spiral path. Cosmic rays are energetic charged particles in outer space, some of which approach the Earth. They can be forced into spiral paths by the Earth’s magnetic field.

3. What is the magnetic effect of electric current?

Answer: When an electric current passes through a wire, it behaves like a magnet. This is the magnetic effect of the electric current. If the electric current does not pass through, it loses its magnetic effect. These coils of wire are called electromagnets.

4. What is Biot Savart law?

Answer: According to this law, the magnitude, length, direction, and proximity of the electric current is related to the magnetic field. It is inversely proportional to the square of the distance of the given point from the current element r.

5. What is the relationship between magnetic force magnetic fields and currents?

Answer: The magnetic force on a current in a magnetic field = current x displacement across the magnetic field. This force can be predicted using the right-hand rule. When two currents are directed through magnetic fields in the same direction, they attract. When they are directed in the opposite direction, they will repel.

These are moving charges and magnetism Important Question Answers – that will help you to score better marks in the exams. Here we have provided you with all types of moving charges and magnetism important question answers & extra solutions, it depends on you how-to catch-up lots of solutions and hard preparation for better performance in your results

Q.1. Are there moving charges in a magnet?

A) Magnetism is essentially a force brought on by moving charges. The orbits of electrons spinning around nuclei are what are thought to be the moving charges in permanent magnets.

Q.2. Which charges can move easily?

A) Conductors are substances that permit the easy passage of negatively charged particles. Several metals are easily conductive to electric current. Silver and copper are excellent conductors.

Q.3. What charges will attract?

A) Unlike charges attract each other whereas like charges repel one another. As a result, a positive charge pulls a negative charge toward it whereas two negative charges repel one another.

Q.4. What is the magnetic effect of current class 12?

A) Moving electric charges and magnetic dipoles combine to form a magnetic field, which acts as a force field on other adjacent moving charges and magnetic dipoles.