When a ferromagnetic material is heated above its Curie temperature it

• gets demagnetised

• becomes diamagnetic

• behaves like a paramagnetic substance

• remains unaffected

A hydrogen atom is paramagnetic. A hydrogen molecule is

• diamagnetic

• paramagnetic

• ferromagnetic

• none of these

A bar magnet of magnetic moment $\overrightarrow{\mathrm{M}}$ is placed in the magnetic field $\overrightarrow{\mathrm{B}}$. The Torque acting on the magnet is :

• $\overrightarrow{\mathbf{M}} \times \overrightarrow{\mathbf{B}}$

• $\overrightarrow{\mathbf{M}} - \overrightarrow{\mathbf{B}}$

• $\frac{1}{2}\overrightarrow{\mathbf{M}} \times \overrightarrow{\mathbf{B}}$

• $\overrightarrow{\mathbf{M}} + \overrightarrow{\mathbf{B}}$

At a certain place, magnitude of horizontal and vertical components of a magnetic field are same. The total intensity of magnetic field at that place will be

• H

• H²

• 2H

• $\sqrt{2 } \mathrm{H}$

The magnetic lines of force inside a bar magnet

• are from north-pole to south-pole of the magnet

• do not exist

• depend upon the area of cross-section of the bar magnet

• are from south-pole to north-pole of the magnet

Curie temperature is the temperature above which

• a ferromagnetic material becomes paramagnetic

• a paramagnetic material becomes diamagnetic

• a ferromagnetic material becomes diamagnetic

• a paramagnetic material becomes ferromagnetic

97.

Which one of the following is ferromagnetic?

• Gold

• Wood

• Manganese

• Nickle

If the earth field induction at a place is 0.36 gauss and the angle of dip is 60°, the horizontal and vertical components of the field will be respectively

• 0.18 gauss, 0.18 $\sqrt{3}$ gauss

• 0.98 gauss, 0.9 $\sqrt{2}$ gauss

• 1.08 gauss, and 1.08 $\sqrt{3}$ gauss

• 1.07 gauss, 0.11 $\sqrt{2}$ gauss

Magnetic field intensify at the centre of coil of 50 turns, 0.5 m radius and carrying a current of 2A, is

• 5x 10^-5 T

• 3 x 10^-5 T

• 1.25 × 10^-4 T

• 0.5 x 10^-5 T

A straight conductor of length 0.4 m is moved with a speed of 7 m/s perpendicular to the magnetic field of intensity of 0.9 Wb/m². The induced emf across the conductor will be

• 7.25 V

• 5.54 V

• 1.25 V

• 2.52 V