Two bar magnets with magnetic moments $ 2 M $ and $M$ are fastened together at right angles to each other at their centres to form a crossed system, which can rotate freely about a vertical axis through the centre. The crossed system sets in earth’s magnetic field with magnet having magnetic moment $2M $ making and angle  $ \theta $ with the magnetic meridian such that

Two short bar magnets oflength $1\ cm$ each have magnetic moments $1.20\ Am^2$ and $1.00\ Am^2$ respectively. They are placed on a horizontal table parallel to each other with their $N$ poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $20.0\ cm$. The value of the resultand horizontal magnetic induction at the mid-point $O$ of the line joining their centres is close to  (Horizontal component of earth.s magnetic induction is $3.6 \times  10^{-5}$ $Wbm^{-2}$  )

Which statement is correct 

Give some of the commonly known ideas regarding magnetism.

What happens when the small bar magnet kept on the glass and iron filings sprinkled on glass ?