The material selected for making a permanent magnet should have:

Paramagnetic substances

A. Move from a region of strong magnetic field to weak magnetic field

B. Has susceptibility less than zero

C. Attract strongly towards external magnetic field

D. Align themselves along the directions of external magnetic field

A bar magnet of length 12 cm is placed such that its north pole points towards the geographic north. Two neutral points which are separated by 16 cm are obtained on the equatorial axis of the bar magnet. What is the pole strength of the bar magnet if the horizontal component of the earth's field is $1.25 \times 10^{-5} \mathrm{~T}$ ?

A short bar magnet placed with its axis at $45^{\circ}$ with an external field of $400 \times 10^{-4} \mathrm{~T}$ experiences a torque of 0.024 Nm . If a solenoid of cross-sectional area $10^{-4} \mathrm{~m}^2$ and 500 turns replaces the short bar magnet such that they have the same magnetic moment, then the current flowing through the solenoid is: