### Physics - Magnetostatics

#### Question - 1

Choose the INCORRECT statement

• A The vertical plane passing through the magnet axis of a freely suspended magnet is called magnetic meridian
• B The strength of magnetic field is measured by dip circle
• C The magnetic potential at any point on the equatorial line of a magnet is zero
• D The ratio of intensities of magnetic fields due to a short magnet in tan A and tan B positions is 2:1

#### Question - 2

By magnetic screening we mean to cut out magnetic fields a small region. The material used for this purpose should be

• A ferromagnetic
• B antiferromagnetic
• C paramagnetic
• D diamagnetic

#### Question - 3

Neel temperature is a temperature

• A below which antiferromagnetism occurs
• B above which the substance is paramagnetic
• C at which there is no net resultant magnetic moment in the absence of an applied magnetic field
• D All of the above statements are correct

#### Question - 4

Angle of dip is maximum at

• A poles
• B equator
• C latitude 45°
• D latitude 60°

#### Question - 5

Choose the INCORRECT statement

• A The ratio of magnetic induction to the intensity of the magnetising filed is called permeability
• B The ratio of the intensity of magnetisation to the intensity of the magnetising field is called susceptibility
• C Magnetic elements of the earth are iron, cobalt and nickel
• D A magnet of pole strength 0.2 ampere-metre when cut into two pieces of equal length has the same pole strength

#### Question - 6

The needle of a dip circle will be vertical if the plane of the dip circle is

• A perpendicular to the magnetic meridian
• B parallel to the magnetic meridian
• C in the magnetic meridian
• D horizontal

#### Question - 7

A magnetic dipole in the shape of a sphere placed in a uniform magnetic field of induction $\overrightarrow { B }$ will, in general

• A be displaced in the direction $\overrightarrow { B }$
• B be displaced opposite to the direction of $\overrightarrow { B }$
• C remain in equilibrium position after displacement from its initial position
• D execute simple harmonic motion provided the amplitude of motion is small

#### Question - 8

The neutral point in a magnetic field is a point at which

• A the field due to the magnet is zero
• B the field due to the magnet and the horizontal intensity of the earth's magnetic field balance each other.
• C the magnetic lines of force from north pole balance those from south pole.
• D the magnetic lines of force do not exist

#### Question - 9

A sphere with a magnetic dipole of moment $\mu$ and a moment of inertia I about its diameter is placed in a uniform magnetic field of induction B. It is capable of oscillating freely about its diameter. For small oscillations, the sphere will experience restoring force per unit mass unit displacement equal to

• A $\sqrt { \frac { I }{ \mu B } }$
• B $\sqrt { \frac { \mu B }{ I } }$
• C $\frac { \mu B }{ I }$
• D $\frac { \mu }{ IB }$

#### Question - 10

The moment of a magnet is 3 ampere-metre2. It is cut into two pieces such that the length of one piece is double the length of the other. The moments of these pieces are in the ratio of

• A 1:2
• B 2:1
• C 1:3
• D 1:1