Note on Magnetic Field and Magnetic Lines of Force

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Magnetic field

The space around a magnet, where magnetic force can be felt by a magnetic body is called the magnetic field of that magnet. The field can be represented by lines, called magnetic lines of force.

A magnetic line of force is a line, straight or curved, the tangent to which at any point gives the direction of the magnetic field at that point.

Properties of magnetic lines of force:

  • Magnetic lines of force start from the North Pole and reach the South Pole externally and then go from the South Pole to the North Pole internally.
  • The magnetic lines of force never intersect.
  • Magnetic lines of force are crowded near the poles, as the field is strong and are widely separated, where the field is weak.

Neutral Point

When two magnetic field i.e. magnetic field of earth's magnet and bar magnet acts in the same place, the resultant field has a special character. When we placed the magnetic needle at any particular point, then the needle does not show any direction at that point as there is no net magnetic field at that point. This point is known as a null point or neutral point.

The given figure A and B show the neutral point. Here, in figure A, when north pole of the magnet points south and magnet in the magnetic meridian, the horizontal component of the earth's magnetic field and bar magnet becomes equal and opposite in point X, which is the neutral point. In figure B, when the north pole of the magnet points geographic north, the neutral point lie towards the lateral side at point X.
A neutral point in a magnetic field is a point at which the horizontal component of earth’s magnetic field and the magnetic field due to the magnet are exactly equal and opposite. At the neutral point, the lines of force will not pass and compass needle will not point in any fixed direction.
In other words, 'A neutral point in a magnetic field is a point at which the horizontal component of earth’s magnetic field and the magnetic field due to the magnet are exactly equal and opposite. At the neutral point, the lines of force will not pass and compass needle will not point in any fixed direction'.

Properties of magnet

  • A magnet attracts magnetic bodies.
  • A freely suspended magnet points north-south direction.
  • Like poles of a magnet repel and unlike poles of a magnet attract.
  • A magnet has two poles: The North Pole and the South Pole.
  • A magnetic material gets magnetized due to the presence of a magnet. It is called magnetic induction.

  • The space around a magnet, where magnetic force can be felt by a magnetic body is called magnetic field of that magnet.
  • A magnetic line of force is a line, straight or curved, the tangent to which at any point gives the direction of the magnetic field at that point.
  • A neutral point in a magnetic field is a point at which the horizontal component of earth’s magnetic field and the magnetic field due to magnet are exactly equal and opposite.
  • The earth’s magnetism is called terrestrial magnetism
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Very Short Questions

The properties of magnetic lines of force are as follows:

(1) Magnetic lines of force start from the North Pole and reach the South Pole externally and then go from South Pole to North Pole internally.
(2) The magnetic lines of force never intersect.
(3) Magnetic lines of force are crowded near the poles, as the field is strong and are widely separated, where the field is weak.

Properties of magnet are as follows:

(1) A magnet attracts magnetic bodies.
(2)Like poles of magnet repel and unlike poles of magnet attract.
(3)A magnetic material gets magnetized due to presence of a magnet. It is called magnetic induction.

A neutral point is a point in the magnetic field of a magnet placed on the surface of the earth at which the resultant field is zero.

A magnetic line of force is a line, straight or curved, the tangent to which at any point gives the direction of the magnetic field at that point.

The earth's magnetism is called terrestrial magnetism. Declination, dip and horizontal component of earth s magnetic field are elements of terrestrial magnetism which helps to locate correct direction.

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  • The point in which earth's magnetic field and magnetic field due to magnet is equal and opposite is called ______.

    nascent point


    active point


    passive point


    neutral point


  • The earth's magnetism is called ______.

    geographical magnetism


    terrestial magnetism


    earth magnetism


    geological magnetism


  • The vertical plane passing through the axis of a freely suspended magnet at a place is called ______.

    magnetic meridian


    magnetic induction


    magnetic moment


    pole strength


  • The angle between the magnetic meridian and geographic meridian at a place is called ______.

    angle of inclination at that place


    angle of dip at that place


    critical angle


    angle of declination at that place


  • The space around a magnet, where magnetic force can be felt by magnetic body is called ______.

    magnetic moment


    magnetic meridian


    magnetic induction


    magnetic field


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Bibek Rai

What does it mean by saying that the angle of dip of Kathmandu is 45°?


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What does it mean by saying that the angle of dip of Kathmandu is 45°?


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Anish Bhattarai

Why magnetic lines are closer at poles?Only reasonable fact answer is required.Explain


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