$(a)$ Magnetic field lines show the direction (at every point) along which a small magnetised needle aligns (at the point). Do the magnetic field lines also represent the lines of force on a moving charged particle at every point?

$(b)$ Magnetic field lines can be entirely confined within the core of a toroid, but not within a straight solenoid. Why?

$(c)$ If magnetic monopoles existed, how would the Gauss’s law of magnetism be modified?

$(d)$ Does a bar magnet exert a torque on itself due to its own field? Does one element of a current-carrying wire exert a force on another element of the same wire?

$(e)$ Magnetic field arises due to charges in motion. Can a system have magnetic moments even though its net charge is zero?

Give some of the commonly known ideas regarding magnetism.

A short magnet of moment $6.75\, Am^2$ produces a neutral point on its axis. If horizontal component of earth's magnetic field is $5 \times {10^{ – 5}}\,Wb/{m^2}$, then the distance of the neutral point should be…..$cm$

A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to:

$A$. hold the sheet there if it is magnetic.

$B$. hold the sheet there if it is non-magnetic.

$C$. move the sheet away from the pole with uniform velocity if it is conducting.

$D$. move the sheet away from the pole with uniform velocity if it is both, non-conducting and non-polar.

Choose the correct statement($s$) from the options given below:

A magnetic needle is kept in a non-uniform magnetic field. It experiences