A magnetic needle suspended horizontally by an unspun silk fibre, oscillates in the horizontal plane because of the restoring force originating mainly from

A closely wound solenoid of $800$ turns and area of cross section $2.5 \times 10^{-4} \;m ^{2}$ carries a current of $3.0\; A .$ Explain the sense in which the solenoid acts like a bar magnet. What is its associated magnetic moment?

Two identical short bar magnets, each having magnetic moment of $10\, Am^2$, are arranged such that their axial lines are perpendicular to each other and their centres be along the same straight line in a horizontal plane. If the distance between their centres is $0.2 \,m$ , the resultant magnetic induction at a point midway between them is$({\mu _0} = 4\pi \times {10^{ – 7}}\,H{m^{ – 1}})$

An iron bar of length $L$ has magnetic moment $M$. It is bent at the middle of its length such that the two arms make an angle $60^{\circ}$ with each other. The magnetic moment of this new magnet is :

The magnetic field due to a short magnet at a point on its axis at distance $X \,cm $ from the middle point of the magnet is $200 $ $Gauss$. The magnetic field at a point on the neutral axis at a distance $ X \,cm$  from the middle of the magnet is…..$Gauss$