Choose the correct statement

• A paramagnetic material tends to move from a strong magnetic field to weak magnetic field

• A magnetic material is in the paramagnetic phase below its Curie temperature

• The resultant magnetic moment in an atom of a diamagnetic substance is zero

• Typical domain size of a ferromagnetic material is 1 nm

The angle of dip at a place is 37° and the vertical component of the earth's magnetic field is 6 x 10^-5 T. The earth's magnetic field at this place is (tan 37° = 3/ 4)

• 7 × 10^-5 T

• 6 × 10^-5 T

• 5 × 10^-5 T

• 10^-4 T

Which one of the following characteristics is not associated with a ferromagnetic material ?

• It is strongly attracted by a magnet

• It tends to move from a region of strong magnetic field to a region of low magnetic field

• Its origin is the spin of electrons

• Above the Curie temperature, it exhibits paramagnetic properties

In a certain place, the horizontal component of magnetic field is $\frac{1}{\sqrt{3}}$ times to vertical component. The angle of dip at this place is

• zero

• $\mathrm{\pi }/3$

• $\mathrm{\pi }/2$

• $\mathrm{\pi }/6$

A paramagnetic substance of susceptibility 3 x 10^-4 is placed in a magnetic field of 4 x10 Am^-1. Then the intensity of magnetization in the units of Am^-1 is

• 1.33 × 10⁸

• 0.75 × 10^-8

• 12 × 10^-8

• 14 × 10^-8

At a temperature of 30°C, the susceptibility of a ferromagnetic material is found to be χ. Its susceptibility at 333°C is 

• χ

• 0.5 χ

• 2 χ

• 0.09 χ

The magnitude of the earth's magnetic field at a place is B₀ and the angle of dip is δ. A horizontal conductor of length l lying magnetic north-south moves eastwards with a velocity v. The emf induced across the conductor is

• zero

• B₀ lv sin δ

• B₀ lv

• B₀ lv cos δ

The examples of diamagnetic, paramagnetic and ferromagnetic materials are respectively

• copper, aluminium, iron

• aluminium, copper, iron

• copper, iron, aluminium

• aluminium, iron, copper

A small rod of bismuth is suspended freely between the poles of a strong electromagnet. It is found to arrange itself at right angles to the magnetic field. This observation establishes that bismuth is

• diamagnetic

• paramagnetic

• ferro-magnetic

• anti ferro-magnetic

20.

The material used for permanent magnet has

• low retentivity, high coercivity

• high retentivity, low coercivity

• high retentivity, high coercivity

• low retentivity, low coercivity