Q: The work done in turning a magnet of magnetic moment \$M\$ by an angle of \$90^{o}\$ from the meridian is \$n\$ times the corresponding work done to turn it through an angle of \$60^{o}\$ from the meridian, where \$n\$ is given by :

Work done in 1st case, \$W_1=MB(cos0^0-cos90^0)\$Work done in 2nd case, \$W_2=MB(cos0^0-cos60^0)\$\$W_1=2W_2\$therefore, \$n=2.\$

Q: A magnet is in stable equilibrium in a uniform magnetic field. It is deflected by \$60^{o}\$ and the workdone is equal to \$W\$. In deflecting the magnet further by \$30^{o}\$, Work done is:

\$U=m.B\$\$U_{1}=-mB\$\$U_{2}=-mB\cos60^o\$\$=\dfrac{-mB}{2}\$\$U_{3}=-mB\cos90^o\$\$=0\$\$W=U_{2}-U_{1}\$\$=\dfrac{mB}{2}\$\$W^{1}=U_{3}-U_{2}\$\$=\dfrac{mB}{2}\$\$W^{1}=W\$

Q: For a paramagnetic material, the dependence of the magnetic susceptibility \$\chi \$ on the absolute temperature T is given by

\$\chi\$ \$=\$ \$\dfrac{c\mu_{o}}{T}\$ (standard equation)\$c=\$ Curie's constant\$\mu _{o}=4\pi \times 10^{-7}\$\$T=\$ Alsolute Temperature\$\chi\$ \$\alpha\$ \$\dfrac{1}{T}\$

Q: A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the center. The substance in the watch glass is (assume poles are far)

Hint: Iron is a ferromagnetic substance. Correct option: A Explanation for correct answer: The substance in the watch glass must be iron as it is a ferromagnetic material.When it is kept in between two pole pieces, it will be attracted by negative one and repelled by positive one and the deep concavity is observed at the center. So, the substance in the watch glass is iron.

Q: Assertion(A): \$\chi -T\$ graph for a diamagnetic material is a straight line parallel to \$T\$ axisReason (R): This is because susceptibility of a diamagnetic material is not affected by temperature

This problem is based on Magnetism.\$\bullet\$ Magnetic Susceptibility is the tendency of a substance to get magnetised when placed in magnetic field. It is denoted by \$\chi\$ pronounced as \$chi.\$ It has no unit.\$\bullet\$ Diamagnetic materials are those which are slightly repelled by a magnet. When placed in a magnetic field they get magnetised in a direction opposite to that of the field. Susceptibility \$\chi\$ of diamagnetic substances is negative.\$\bullet\$ However, their susceptibility shows negligible change when heated or cooled. Their \$\chi\$ remains unchanged with change in temperature. Temperature is denoted by \$T.\$Now look at the diagram.It is a graph of susceptibility with respect to temperature for a diamagnetic material. Temperature is in Celcius.The green line shows the change in \$\chi\$ with respect to \$T.\$You can see that it is almost parallel to the \$T\$ axis.Since\$\chi\$ is negative and \$T\$ is positive, the line is in the 4th quadrant.

Q: The incorrect statement regarding the lines of force of the magnetic field B is:

\$\rightarrow\$ Magnetic intensity is proportional to the number of magnetic field lines.\$\rightarrow\$ Magnetic field lines of forces are closed curves.\$\rightarrow\$ Inside the magnet, field lines move from the South Pole to the North Pole.\$\rightarrow\$ Magnetic lines of force never cut each other.Therefore, option C is incorrect

Question 1

Assertion(A) : The ferro magnetic substances do not obey curie's law.Reason(R) : At curie point ferromagnetic substances start behaving as a paramagnetic substances.

Accepted Answer

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Question 2

For soft iron, in comparison with steel :

Accepted Answer

Soft iron has less hysteresis losses than steel. due to soft irons low corecivity and high retentivity.

Question 3

The work done in turning a magnet of magnetic moment $M$ by an angle of $9 0^{o}$ from the meridian is $n$ times the corresponding work done to turn it through an angle of $6 0^{o}$ from the meridian, where $n$ is given by :

Accepted Answer

Work done in 1st case, $W_1=MB(cos0^0-cos90^0)$Work done in 2nd case, $W_2=MB(cos0^0-cos60^0)$$W_1=2W_2$therefore, $n=2.$

Question 4

A magnet is in stable equilibrium in a uniform magnetic field. It is deflected by $60^{o}$ and the workdone is equal to $W$. In deflecting the magnet further by $30^{o}$, Work done is:

Accepted Answer

$U=m.B$$U_{1}=-mB$$U_{2}=-mB\cos60^o$$=\dfrac{-mB}{2}$$U_{3}=-mB\cos90^o$$=0$$W=U_{2}-U_{1}$$=\dfrac{mB}{2}$$W^{1}=U_{3}-U_{2}$$=\dfrac{mB}{2}$$W^{1}=W$

Question 5

The lines of force of a bar magnet are:

Accepted Answer

Lines of force of bar magnet are closed curved loops as shown in the attached figure.

Question 6

The area enclosed by a hysteresis loop is a measure of

Accepted Answer

Hint:  The area enclosed by a hysteresis loop is a measure of  energy loss  per cycle.&#10;&#10;Correct option: D&#10;&#10;Explanation for correct answer:&#10;&#10;From the given hysteresis loop, we can notice that&#10;the material gets magnetized and demagnetized in one cycle. In this process the&#10;energy is lost.&#10;&#10;So, hysteresis loop signifies the energy loss per cycle.

Question 7

For a paramagnetic material, the dependence of the magnetic susceptibility $\chi $ on the absolute temperature T is given by

Accepted Answer

$\chi$ $=$ $\dfrac{c\mu_{o}}{T}$   (standard equation)$c=$ Curie's constant$\mu _{o}=4\pi \times 10^{-7}$$T=$ Alsolute Temperature$\chi$ $\alpha$ $\dfrac{1}{T}$

Question 8

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the center. The substance in the watch glass is (assume poles are far)

Accepted Answer

Hint: Iron is a ferromagnetic substance.&#10;&#10;Correct option: A&#10;&#10;Explanation for correct answer:&#10;&#10;The substance in the watch glass must be iron as&#10;it is a ferromagnetic material.When it is kept in between two pole pieces, it&#10;will be attracted by negative one and repelled by positive one and the deep concavity&#10;is observed at the center.&#10;&#10;&#10;&#10;So, the substance in the watch glass&#10;is iron.

Question 9

Assertion(A): $\chi -T$ graph for a diamagnetic material is a straight line parallel to $T$ axisReason (R): This is because susceptibility of a diamagnetic material is not affected by temperature

Accepted Answer

This problem is based on Magnetism.$\bullet$ Magnetic Susceptibility is the tendency of a substance to get magnetised when placed in magnetic field. It is denoted by $\chi$ pronounced as $chi.$ It has no unit.$\bullet$ Diamagnetic materials are those which are slightly repelled by a magnet. When placed in a magnetic field they get magnetised in a direction opposite to that of the field. Susceptibility $\chi$ of diamagnetic substances is negative.$\bullet$ However, their susceptibility shows negligible change when heated or cooled. Their $\chi$ remains unchanged with change in temperature. Temperature is denoted by $T.$Now look at the diagram.It is a graph of susceptibility with respect to temperature for a diamagnetic material. Temperature is in Celcius.The green line shows the change in $\chi$ with respect to $T.$You can see that it is almost parallel to the $T$ axis.Since$\chi$ is negative and $T$ is positive, the line is in the 4th quadrant.

Question 10

The incorrect statement regarding the lines of force of the magnetic field B is:

Accepted Answer

$\rightarrow$ Magnetic intensity is proportional to the number of magnetic field lines.$\rightarrow$ Magnetic field lines of forces are closed curves.$\rightarrow$ Inside the magnet, field lines move from the South Pole to the North Pole.$\rightarrow$ Magnetic lines of force never cut each other.Therefore, option C is incorrect

Magnetism And Matter

Physics
1952 Views

Assertion(A) : The ferro magnetic substances do not obey curie's law.
Reason(R) : At curie point ferromagnetic substances start behaving as a paramagnetic substances.

For soft iron, in comparison with steel :

The work done in turning a magnet of magnetic moment $M$ by an angle of $9 0^{o}$ from the meridian is $n$ times the corresponding work done to turn it through an angle of $6 0^{o}$ from the meridian, where $n$ is given by :

A magnet is in stable equilibrium in a uniform magnetic field. It is deflected by $6 0^{o}$ and the workdone is equal to $W$ . In deflecting the magnet further by $3 0^{o}$ , Work done is:

The lines of force of a bar magnet are:

The area enclosed by a hysteresis loop is a measure of

For a paramagnetic material, the dependence of the magnetic susceptibility $χ$ on the absolute temperature T is given by

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the center. The substance in the watch glass is (assume poles are far)

Assertion(A): $χ - T$ graph for a diamagnetic material is a straight line parallel to $T$ axis
Reason (R): This is because susceptibility of a diamagnetic material is not affected by temperature

The incorrect statement regarding the lines of force of the magnetic field B is:

Magnetism And Matter

Physics 1952 Views

Assertion(A) : The ferro magnetic substances do not obey curie's law. Reason(R) : At curie point ferromagnetic substances start behaving as a paramagnetic substances.

For soft iron, in comparison with steel :

The work done in turning a magnet of magnetic moment M by an angle of 90o from the meridian is n times the corresponding work done to turn it through an angle of 60o from the meridian, where n is given by :

A magnet is in stable equilibrium in a uniform magnetic field. It is deflected by 60o and the workdone is equal to W. In deflecting the magnet further by 30o, Work done is:

The lines of force of a bar magnet are:

The area enclosed by a hysteresis loop is a measure of

For a paramagnetic material, the dependence of the magnetic susceptibility χ on the absolute temperature T is given by

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the center. The substance in the watch glass is (assume poles are far)

Assertion(A): χ−T graph for a diamagnetic material is a straight line parallel to T axis Reason (R): This is because susceptibility of a diamagnetic material is not affected by temperature

The incorrect statement regarding the lines of force of the magnetic field B is:

Physics
1952 Views

Assertion(A) : The ferro magnetic substances do not obey curie's law.
Reason(R) : At curie point ferromagnetic substances start behaving as a paramagnetic substances.

The work done in turning a magnet of magnetic moment $M$ by an angle of $9 0^{o}$ from the meridian is $n$ times the corresponding work done to turn it through an angle of $6 0^{o}$ from the meridian, where $n$ is given by :

A magnet is in stable equilibrium in a uniform magnetic field. It is deflected by $6 0^{o}$ and the workdone is equal to $W$ . In deflecting the magnet further by $3 0^{o}$ , Work done is:

For a paramagnetic material, the dependence of the magnetic susceptibility $χ$ on the absolute temperature T is given by

Assertion(A): $χ - T$ graph for a diamagnetic material is a straight line parallel to $T$ axis
Reason (R): This is because susceptibility of a diamagnetic material is not affected by temperature