Magnetic Field Lines - Practice Questions & MCQ

Important points regarding Magnetism-

• The earth behaves as a magnet with the magnetic field lines pointing from the geographic south to the north.
• When a bar magnet is freely suspended, it points in the north-south direction. The tip which points to the geographic north is called the north pole and the tip which points to the geographic south is called the south pole of the magnet.
• There is a repulsive force when like poles of two magnets are brought close together and there is an attractive force when unlike poles of two magnets are brought close together.
• The north and south pole cannot be separated by splitting the magnet into two parts.

         i.e. If a magnet is broken into a number of pieces each piece becomes a magnet.

• It is possible to make magnets out of iron and its alloys.

Magnetic field-

Space around a magnetic Pole or magnet or current-carrying wire within which its effect can be experienced.

Magnetic field lines-

The magnetic field line is not real. The magnetic field lines are a visual and intuitive realization of the magnetic field.

Properties of magnetic field lines-

• The magnetic field lines of a magnet form continuous closed loops. Outside the magnet, magnetic field lines start from the north pole and end at the south pole, whereas inside the magnet its direction is from south pole to north pole.
• The tangent to the magnetic field line at a given point represents the direction of the net magnetic field ($\overrightarrow{B}$) at that point.

       For the below figure, the tangent to the magnetic field line at point P represents the direction of the net magnetic field ($\overrightarrow{B}$) at point P.

• The larger the number of magnetic field lines crossing per unit area, the stronger is the magnitude of the magnetic field ($\overrightarrow{B}$) at that region.
• The two magnetic field lines do not intersect at any point.