Magnetism and matter practice · Mixed difficulty

A long copper tube of inner radius ${R}$ carries a current $i$. The magnetic field $B$ inside the tube is

The material used for permanent magnet has :

Magnetic lines of force due to a bar magnet do
not intersect because

Assertion (A): Time period of vibrations of a pair of magnets in sum position is always smaller than in difference position.

Reason (R): $\mathrm{T}=2 \pi \sqrt{I / M B_H}$, where symbols have their standard meaning.

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the centre. The substance in the watch glass is

The relative permeability $(\mu_r)$ of a substance is related to its susceptibility $(\chi)$ as

The relation between $\mu$ and $H$ for a specimen of iron is given by $\mu = \left( {\frac{{0.8}}{H} + 8 \times {{10}^{ - 4}}} \right)H/m.$ The value of $H$ which produces flux density of 1 tesla will be

A magnet of magnetic moment 20 CGS units is freely suspended in a uniform magnetic field of intensity 0.3 CGS units. The amount of work done in deflecting it by an angle of $30^\circ$ in CGS units is

The Curie's law is given as (symbols have their usual meanings)

The temperature, above which a ferromagnetic material becomes paramagnetic, is called

A bar magnet has magnetic moment $M$. If a hole is drilled normally through the centre of length of magnet, then the new magnetic moment of the magnet is

The material for which the atoms have permanent magnetic moment and are organised in domains?

Given below are three statements.

Statement-A : Every magnetic configuration
must have a north and a south
pole.

Statement-B : Net magnetic flux through any
closed surface is zero, but net
electric flux may not be zero.

Statement-C : Materials showing Meissner
effect have zero magnetic
susceptibility.

In light of the above statements, choose the
correct answer from the options given below.

Assertion: If a compass needle be kept at magnetic north pole of the earth, the compass needle may stay in any direction
Reason: Dip needle will stay vertical at the north pole of earth.

When a magnet is placed vertically on horizontal board, number of neutral points obtained on the board is

If $\mathrm{B_H}=4 \times 10^{-5} \mathrm{~T}$ and $\mathrm{B}_{\mathrm{V}}=2 \times 10^{-5} \mathrm{~T}$, then the Earth's total field (in $\mathrm{T}$) at the place is

The value of angle of dip is zero at the magnetic equator because on it

Coercivity and retentivity of soft iron is

The angle of dip if dip needle oscillating in vertical plane makes 40 oscillations per minute in a magnetic meridian and 30 oscillations per minute in vertical plane at right angle to the magnetic meridian is

Assertion(A): If one arm of a U-tube containing a dia magnetic solution is placed in between the poles of a strong magnet with the level in line with the field, the level of the solution falls,

Reason(R): Diamagnetic substances are repelled by the magnetic field.

Magnetic susceptibility for a paramagnetic and diamagnetic materials is respectively

The time period of a freely suspended bar magnet in a field is 2 s. It is cut into two equal parts along its axis, then the time period is

The time period of a bar magnet suspended horizontally in the earth’s magnetic field and allowed to oscillate

For protecting a sensitive equipment from the external magnetic field, it should be

Consider the following statements:

1. If a piece of bar magnet is broken into two equally long pieces, the pieces will not lose the magnetic properties

2. Magnetic properties of a substance lie in the atomic level

Which of the statements given above is/are correct?

The angle which the total magnetic field of
earth makes with the surface of the earth is
called

The magnetic intensity $H$ at the centre of a long solenoid carrying a current of $2.0 \mathrm{~A}$, is found to be $1500 \mathrm{~A} \mathrm{~m}^{-1}$. Find the number of turns per centimetre of the solenoid.

Identify the correctly matched pair in the following.

A vibration magnetometer consists of two identical bar magnets placed one over the other such that they are perpendicular and bisect each other. The time period of oscillation in a horizontal magnetic field is ${2^{5/4}}$ second. One of the magnets is removed and if the other magnet oscillates in the same field, then the time period in second is

There is no couple acting when two bar
magnets are placed coaxially separated by a
distance because