What happens to the force between two magnetic poles when their pole strength and the distance between them are both doubled?

$A$ bar magnet is cut into two equal parts. Then,which of the following quantities may change?

Verify Ampere's law for the magnetic field of a point dipole with dipole moment $\vec{M} = M\hat{k}$. Take $C$ as the closed curve running clockwise along the $z$-axis from $z = a > 0$ to $z = R$,then along the circular arc of radius $R$ to the $x$-axis,then along the $x$-axis to $x = a$,and finally along the circular arc of radius $a$ back to the $z$-axis.

The resultant magnetic moment of three magnetic dipoles,each of magnetic moment $M$,shown in the arrangement is:

The magnetic field due to a short bar magnet of magnetic dipole moment $M$ and length $2l$,on the axis at a distance $Z$ (where $Z \gg l$) from the centre of the magnet is given by . . . . . . .

Write the difference between electric field lines and magnetic field lines.