Embibe Experts Solutions for Chapter: Matter and Magnetism, Exercise 2: Exercise-2

A bar magnet having a magnetic moment of $2\times {10}^4 \mathrm{J} {\mathrm{T}}^{-1}$ is free to rotate in a horizontal plane. A horizontal magnetic field $B=6\times {10}^{-4} \mathrm{T}$ exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction $60°$ from the field is

Two identical bar magnets are fixed with their centres at a distance $\mathrm{d}$ apart. A stationary charge $\mathrm{Q}$ is placed at $P$ in between the gap of the two magnets at a distance $D$ form the center  $O$ as shown in the figure

The force on the charge is

There are four light-weight-rod samples, $A, B, C, D$ separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted.
i. $A$ is feebly repelled.
ii. $B$ is feebly attracted.
iii. $C$ is strongly attracted.
iv. $D$ remains unaffected. 
Which one of the following is true?

A short bar magnet of magnetic moment $0.4 \mathrm{J} {\mathrm{T}}^{-1}$ is placed in a uniform magnetic field of $0.16 \mathrm{T}$. The magnet is stable equilibrium when the potential energy is:

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole $\overrightarrow{m}$. Which configuration has highest net magnetic dipole moment?

(a)(b)(C)(d)

At a point $A$ on the earth's surface of angle of dip, $\delta =+25°.$ At a point $B$ on the earth's surface the angle of dip, $\delta =-25°.$ We can interpret that:

The coercivity of a small magnet where the ferromagnet gets demagnetized is $3\times {10}^3 \mathrm{A} {\mathrm{m}}^{-1}.$ The current required to be passed in a solenoid of length $20 \mathrm{cm}$ and number of turns $100 ,$ so that the magnetic gets demagnetized when inside the solenoid, is___

Hysteresis loops for two magnetic materials $A$ and $B$ are given below:

(A)(B)

These materials are used to make magnets for electric generators, transformer cores and electromagnet cores. Then it is proper to use