Question 1 :
The relative permeability of a substance X is slightly less than unity and that of substance Y is slightly more than unity, then :<br/>
Question 2 :
A dipole of magnetic moment $2\ A-m^{2}$ is deflected through $30^{o}$ from magnetic meridian. If magnetic field strength of Earth's horizontal component is $H=30\ A/m$, the deflecting couple is
Question 3 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A bar magnet is cut into two equal halves by a plane parallel to the magnetic axis. From the given following physical quantities, which remains unchanged is :</p>
Question 4 :
The magnetic moment produced in a substance of 1 g is $6 \times 10^{-7}\, A-m^2$. If its density is $5 \,\,g/cm^3$, then the intensity of magnetisation in A/m will be :<br/>
Question 5 :
Magnetic field intensity $H$ at the centre of a circular loop of radius $r$ carrying current $I$ in emu system <span>is</span>
Question 6 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p class="wysiwyg-text-align-left">A bar magnet of length 0.2 m and pole strength 5 A.m. should be kept in a uniform magnetic field of induction 15 tesla at angle ..... radians to the field so that the torque experienced by it will be 7.5N-m</p></span></span>
Question 8 : <p class="wysiwyg-text-align-left"><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">Relation between $\vec{H},\vec{I}$ </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">and</span></span><span class="wysiwyg-font-size-large"><span class="wysiwyg-font-size-large"></span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"> $\vec{B}$ is :<br/></span></span></p>
Question 9 :
Torques ${ \tau }_{ 1 }$ and ${ \tau }_{ 2 }$ are required for a magnetic needle to remain perpendicular to the magnetic fields at two different places. The magnetic fields at those places are ${B}_{1}$ and ${B}_{2}$ respectively; then ratio $\cfrac{{B}_{1}}{{B}_{2}}$ is
Question 10 :
Two bar magnet are kept together and suspended freely in earth's magnetic field. When both like poles are aligned, the time period is 6 sec. When opposite poles are aligned, the time period is 12 sec. The ratio of magnetic moments of the two magnets is :
Question 11 :
The intensity of a magnetic field is defined as the force experienced by a
Question 12 :
When orientation of dipoles parallel and antiparallel to magnetic field is distributed unequally, then the material is
Question 15 : When a bar magnet is suspended in a uniform magnetic field, the torque acting on it will be :<br/><table class="wysiwyg-table"><tbody><tr><td>a) maximum</td><td>e) $\theta=45^o$ with the field</td></tr><tr><td>b) half the maximum field</td><td>f) $\theta=60^o$ with the field</td></tr><tr><td>c) $\sqrt{3}/2$ times the maximum field</td><td>g) $\theta=30^o$ with the field</td></tr><tr><td>d) $1/\sqrt{2}$ times the maximum field</td><td>h) $\theta=90^o$ with the field</td></tr></tbody></table>
Question 16 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A magnetic needle is kept in a non uniform magnetic field. It experiences :<br/></p>
Question 17 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">Permeability of a material is $0.872$. This material is then</p>
Question 18 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A bar magnet of magnetic moment $M$ and moment of inertia I is freely suspended such that the magnetic axial line is in the direction of magnetic meridian. If the magnet is displaced by a very small angle $(\theta )$ , the angular acceleration is (Magnetic induction of earths horizontal field $ = $ $B_H$)<br></p>
Question 20 :
The area of $I-H$ curve and area of $B-H$ curve are related as.
Question 22 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p class="wysiwyg-text-align-left">When a bar magnet is suspended freely in a uniform magnetic field, identify the correct statements:</p><p class="wysiwyg-text-align-left">a) The magnet experiences only couple and undergoes only rotatory motion</p><p class="wysiwyg-text-align-left">b) The direction of torque is along the suspension wire</p><p class="wysiwyg-text-align-left">c) The magnitude of torque is maximum when the magnet is normal to the field direction</p></span></span>
Question 23 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">Two points A and B equidistant from the centre of <span>a small bar magnet. Point ‘A’ is on the axial line </span><span>and point ‘B’ is on the equatorial line. Then the </span><span>magnetic fields at point ‘A’ and ‘B’ are in the ratio </span><span>of</span></p>
Question 24 :
If ${\mu}_{0}$ is absolute permeability of vacuum and ${\mu}_{r}$ is relative magnetic permeability of another medium, then permeability $\mu$ of the medium is
Question 25 :
A bar magnet is cut into two equal haves by a plane parallel to the magnetic axis. Of the following physical quantities the one which remains unchanged is
Question 26 :
A bar magnet of dipole moment M is initially parallel to a magnetic field of induction B. The angle through which it should be rotated so that the torque acting on it is half the maximum torque is _____.
Question 29 :
Relative permitivity and permability of a material ${ \varepsilon }_{ r }$ and ${ \mu }_{ r }$ respectively. Which of the following values of these quantities are allowed for a diamagnetic material?
Question 30 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">When a bar magnet is placed perpendicular to a uniform a magnetic field, it is acted upon by a couple of magnitude $1.732\times 10^{-5}Nm$. The angle through which the magnet should be turned so that the couple acting on it becomes $1.5\times 10^{-5}Nm$ is<br/></p>
Question 31 :
A short bar magnet produces magnetic fields of equal induction at two points one on the axial line and the other on the equatorial line. The ratio of their distances is
Question 32 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p class="wysiwyg-text-align-left">An iron specimen has relative permeability of 600 when placed in uniform magnetic field of intensity 110 amp. /m. Then the magnetic flux density inside is....... tesla.</p></span></span>
Question 33 :
A long solenoid has 1000 turns per meter and carries a current of 1 A. It has a soft Iron core of $ u_{r}= 1000 $. The core is heated beyond the Curie temperature, $ T_{e^{-}} $
Question 35 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">If the maximum couple acting on magnet in a field of induction $0.2 T$ is $10\ Nm$, its magnetic moment is</p>
Question 38 :
The value of relative magnetic permeability $(\mu_r$) for ferromagnetic materials is
Question 39 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">Magnetic induction at a point on the axial line of a short bar magnet is $B$ towards East. If the <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">magnet is turned through $90^o$</span></span><span class="wysiwyg-font-size-xx-small"><span class="wysiwyg-font-size-xx-small"> </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">in clock wise </span></span>direction, then magnetic induction at the same point is (Neglect Earth's magnetic field).</p>
Question 40 :
When a bar magnet is placed at 90$^{o}$ in a uniform magnetic field, then it is acted upon by a maximum couple. For the couple to be half the maximum value, the magnet should be inclined to the magnetic field at an angle of :<br/>
Question 41 :
The relation between $B, H$ and $I$ in S.I units is :<br/>
Question 42 :
The intensity of magnetic fields at a distance $d$ from an isolated pole of $m$ units in the air is
Question 44 :
A bar magnet has a magnetic moment of $200$ $A{m}^{2}$. The magnet is suspended in a magnetic field of $0.30\ N{A}^{-1}{m}^{-1}$. The torque required to rotate the magnet from its equilibrium position through an angle of ${30}^{o}$ will be:
Question 45 :
A bar magnet of magnetic moment $\overrightarrow{M}$, is placed in magnetic field of induction $\overrightarrow{B}$. The torque exerted on it is
Question 46 :
The ratio of magnetic induction of magnetic field strength in a medium gives magnetic permeability.<br>
Question 47 :
The gyro-magnetic ratio of an electron in an H-atom, according to Bohr's model, is
Question 49 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A short bar magnet produces magnetic fields of equal induction at two points on the axial line and the other on the equatorial line. Then the ratio of the distance is <br/></p>
Question 50 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A bar magnet of length $16 cm$ has a pole strength of $500\times 10^{-3}Am$ The angle at which it should be placed to the direction of external magnetic field of induction $2.5 G$ so that it may <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">experience a torque of $\sqrt{3}\times 10^{-5}$</span></span><span class="wysiwyg-font-size-xx-small"><span class="wysiwyg-font-size-xx-small"> </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">Nm is :<br/></span></span></p>
Question 51 :
Two small magnets have their masses and lengths in the ratio $1 : 2$. The maximum torques experienced by them in a uniform magnetic field are the same. For small oscillations, the ratio of their time periods is
Question 52 : <p>The relation between magnetic permeability, $\mu$ and field strength, $H$ for a specimen of iron is as follows $\mu =\left [ \dfrac{0.4}{H}+12\times 10^{-4} \right ]$ Henry / meter. The value of $H$ which produces flux density of $1T$ will be :<br/></p>
Question 53 :
The mass of an iron rod is $80$ $gm$ and its magnetic moment is $10$ $Am^2$. If the density iron is $8$ ${gm/cc}$, then the value of intensity of magnetization will be
Question 54 :
A bar magnet of magnetic moment M is placed in the magnetic field B. The torque acting on the magnet is :
Question 55 :
Assertion: In water, value of magnetic field decreases.
Reason: Water is a diamagnetic substance
Question 56 :
A magnetic induction due to a short bar magnetic of magnetic moment $5.4 A {m}^{2}$ at a distance of $30 cm$ on the equatorial line is
Question 57 :
The distance of two points on the axis of a magnet from its center are $10$cm . The ratio of magnetic field at these points is $12.5:1$. The length of the magnet is :
Question 58 :
The period of oscillation of a thin magnet at a place is $T$. When it is stretched to double its length and its pole strength is reduced to $\dfrac { 1 }{ 4 } $ of its initial value, then its period of oscillation is:
Question 59 :
A magnetic needle lying parallel to a magnetic field requires W units of work to turn it through $60^{o}$. The torque needed to maintain the needle in this position will be
Question 60 :
Magnetic induction due to magnetic monopole is inversely proportional to cube of distance of the point.<br>
Question 61 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A magnet of length $10\ cm$ and pole strength $4 \times 10^{-4} \ A.m$ is placed in a magnetic field of induction $2\times 10^{-5}\ Wb- m^{-2}$, such that the axis of the magnet makes an angle $30^{o}$ with the lines of induction. The moment of the couple acting on the magnet is<br/></p>
Question 62 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">Match the following :</p><table class="wysiwyg-table"><tbody><tr><td>LIST - 1 </td><td>LIST- 2</td></tr><tr><td>a) Magnetic moment</td><td>d)$Am^{2}$</td></tr><tr><td>b) Pole strength</td><td><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">e) $Am$</span></span></td></tr><tr><td>c)Permeability</td><td>f) $Wb$</td></tr><tr><td></td><td>g)$\dfrac{Wb}{Am}$</td></tr><tr><td></td><td>h)$\dfrac{H}{m}$</td></tr></tbody></table><span class="wysiwyg-font-size-medium"></span><p></p><p></p>
Question 63 :
The relative permeability of glass is 3$/ 8$ and the dielectric constant of glass is 8. The refractive <span>index of glass is</span>
Question 64 :
Match the following and select the correct alternatives given below<br>(p) unit of magnetic induction B (q) dimensions of B<br>(r) unit of permeability $({\mu}_{o})$ (s) dimensions of ${\mu}_{o}$<br>(t) dimensions of magnetic moment (u) $[ML{T}^{-2}{A}^{-2}]$<br>(v) $[M{L}^{0}{T}^{-2}{A}^{-2}]$ (x) Newton/amp-metre<br>(y) $Newton/{amp}^{2}$ (z) $[{M}^{0}{L}^{2}{T}^{0}A]$
Question 65 : <p class="wysiwyg-text-align-left"><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">A bar magnet of moment $\overline{M}=\hat{i}+\hat{j}$ is placed </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">in a magnetic field induction $\vec{B}=3\hat{i}+4\hat{j}+4\hat{k}$</span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">.</span></span></p><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p>The torque acting on the magnet is</p></span></span>
Question 67 :
A proton with kinetic energy K describes a circle of radius r in a uniform magnetic. An $\alpha$- particle with kinetic energy K moving in the same magnetic field will describe a circle of radius?
Question 68 :
Find the magnitude of magnetic field and it's direction with respect to line joining the center of dipole and a point. The dipole has a magnetic moment $1.2\ Am^2$, and point is $1\ m$ away from it and making an angle $60^\circ{}$ with axis of the dipole. <br/>
Question 69 :
A bar magnet has length $3\ cm$, cross-sectional area $2\ cm^{2}$ and magnetic moment $3Am^{2}$. The intensity of magnetisation of bar magnet is
Question 71 :
A magnetic needle suspended parallel to a magnetic field requires $\sqrt 3 J$ of work to turn it through $60^o$. The torque needed to maintain the needle in this position will be<br>
Question 72 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">The dipole moment of each molecule of paramagnetic gas is $1.5\times 10^{-23}A.m^{2}$ at $27^{o}C$ and the number of molecules per unit volume in it is $2\times 10^{26}m^{-3}.$ The maximum possible intensity of magnetisation at $27^{o}C$ in the gas will be (in $A/m$)<br/></p>
Question 73 :
A short bar magnet experiences a torque of magnitude $0.64\ J$. When it is placed in a uniform magnetic field of $0.32\ T$, making an angle of $30^{\circ}$ with the direction of the field. The magnetic moment of the magnet is
Question 74 :
The distance of two points on the axis of a magnet from its center is $10 \mathrm{cm} $ and $ 20\mathrm{cm} $ respectively. The ratio of magnetic intensity at these points is $ 12.5 : 1 $ The length of the magnet will be
Question 76 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p>A bar magnet with poles $25$ $cm$ apart and pole strength $14.4$ $A-m$ rests with it's center on a<span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"> friction less pivot. If it is held in equilibrium at $60^{0}$</span></span><span class="wysiwyg-font-size-xx-small"><span class="wysiwyg-font-size-xx-small"></span></span> to a uniform magnetic field on induction $0.25$ $T$ by applying a force $F$ at right angles to it's axis $10$ $cm$ from the pivot, then the value of $F$ in Newton is (nearly)</p>
Question 77 :
Assertion : The ability of a material to permit the passage of magnetic lines of force through it is called magnetic permeability.<br>Reason : For a perfect diamagnetic substance, permeability is always one.
Question 78 :
When a certain length of wire is turned into one circular loop. tire magnetic induction at the centre of coil due to some current flowing is ${ B }_{ 1 }$, If the same wire is turned into three loops to make a circular coil. the magnetic induction at the center of this coil for the same current will be
Question 79 :
Assertion: When a magnetic dipole is placed in a non uniform magnetic field, only a torque acts on the dipole.
Reason: Force would also acts on dipole if magnetic field were uniform.
Question 80 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">An iron rod of cross sectional area $4\ sq.cm$. is placed with its length parallel to a magnetic field of intensity $160\ A/m$. The flux through the rod is $4 \times 10^{-4}\ Wb$. Then the permeability of the material of the rod is :</p><p class="wysiwyg-text-align-left"> [in $Wb /(A-m)$]<br/></p>
Question 82 :
A bar magnet has a magnetic moment of $200$ A $m^2$. The magnet is suspended in a magnetic field of $0.30$N $A^{-1}m^{-1}$. The torque required to rotate the magnet from its equilibrium position through an angle of $30^o$, will be:
Question 83 :
A magnet of magnetic moment $50\hat{i} A-m^2$ is placed along x- axis in a magnetic field$ \overrightarrow {B} =( 0.5 \hat{i} + 3.0 \hat{j})$ tesla. The torque acting on the magnet is
Question 84 :
The magnetic susceptibility of a paramagnetic substance is $3 \times 10^{-4} Am^{-1}$. The intensity of magnetisation will be : ( $H = 4 \times 10^3$ )
Question 85 :
A paramagnetic sample shows a net magnetization of $0.8\ A m^{-1}$, when placed in an external magnetic field of strength $0.8\ T$ at a temperature $5\ K$. When the same sample is placed in an external magnetic <span>field of $0.4\ T$ at a temperature of $20\ K$, the magnetization is:</span>
Question 86 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"><p class="wysiwyg-text-align-left">The magnetic moment of a magnet <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">$(10cm\times 2cm\times 1cm)$ is $1A-m^{2}$</span></span><span class="wysiwyg-font-size-xx-small"><span class="wysiwyg-font-size-xx-small"> </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">. The intensity </span></span>of magnetisation is </p></span></span>
Question 87 :
Rate of change of torque $ \tau $ with deflection $ \theta $ is maximum for a magnet suspended freely in a uniform magnetic field of induction $ B $, when
Question 88 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A magnet has a dimensions of 25 cm $\times$ 10 cm $\times$ 5 cm and pole strength of $200\times 10^{-3}$Am The intensity of magnetization due to it is :<span><br/></span></p>
Question 89 :
The magnetic moment of a magnet is $0.25 A-m^2$. It is suspended in a magnetic field of intensity $2\times 10^{-5}T$. The torque acting on it when deflected by $30^0$ from the magnetic field is :
Question 90 :
<span>The ability of a material to remain magnetized after removal of the magnetizing force is known as</span>
Question 91 : <p class="wysiwyg-text-align-left">The rate of change of torque $\tau $ with deflection $\theta $ is maximum for a magnet suspended freely in a uniform magnetic field of induction B when $\theta $ is equal to<br/></p>
Question 93 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A bar magnet of pole strength 50 A.m. is cut into 10 equal parts parallel to its axial line. The intensity of magnetisation of each piece will be :</p>
Question 94 :
The moment of a magnet ($15cm\times 2cm\times 1cm$) is $1.2A{m}^{2}$. What is its intensity of magnetisation?
Question 95 :
The magnetic susceptibility of a paramagnetic material at $73^o$C is $0.0075$. Then its value at $173^o$C will be
Question 96 :
The magnetic induction at a distance of 20cm on the equatorial line of a short bar magnet with a magnetic moment 60 Am$^{2}$ is
Question 98 :
If relative permeability of iron is 2000. Its absolute permeability in S.I units is
Question 99 :
The couple acting on a bar magnet of pole strength $2\ \text{Am}$ when kept in a magnetic field of intensity $10\ \text{A/m}$, such that axis of the magnet makes an angle $30^{o}$ with the direction of the field is $80\times 10^{-7}\ \text{Nm}$. The distance between the poles of the magnet is :<br/>
Question 100 : <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium"></span></span><p class="wysiwyg-text-align-left">A bar magnet of length $10 cm$ experiences a torque of $\dfrac{\sqrt{2}}{10} Nm$ in an uniform magnetic field <span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">of induction $0.4 Wb/m^{2}$</span></span><span class="wysiwyg-font-size-xx-small"><span class="wysiwyg-font-size-xx-small"> </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">when it is suspended </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">making an angle $45^{o}$</span></span><span class="wysiwyg-font-size-xx-small"><span class="wysiwyg-font-size-xx-small"> </span></span><span class="wysiwyg-font-size-medium"><span class="wysiwyg-font-size-medium">with the field. The pole </span></span>strength of the magnet is ( in $Am$) :<br/></p>
