MCQs from NCERT Exemplar

Class 10
Chapter 13 Class 10 - Magnetic Effects of Electric Current

## (d) Relative strength of magnetic field is shown by the degree of closeness of the field lines.

Magnetic field lines are imaginary lines along which the north magnetic pole would move in a magnetic field.

Characteristics of magnetic field lines are:

• Field lines arise from the North pole and end into the South pole of the magnet.
• Field lines are closed curves.
• Field lines are closer in stronger magnetic fields.
• Field lines never intersect each other as for two lines to intersect, there must be two directions of magnetic field  at a point, which is not possible.
• Direction of field lines inside a magnet is from South to North.
• The relative strength of the magnetic field is shown by the degree of closeness of field lines.

Checking the options:

• (a) The direction of the magnetic field at a point is taken  to be the direction in which the north pole of a  magnetic compass needle points - This is correct
• (b) Magnetic field lines are closed curves - This is correct
• (c) If magnetic field lines are parallel and equidistant,  they represent zero field strength - This is incorrect
• (d) Relative strength of magnetic field is shown by  the degree of closeness of the field lines - This is correct

So, the correct answer is (c)