Recent questions tagged ncert

Give two examples of magnetic dipole

asked Jul 21, 2015 by meena.p

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Why do magnetic lines of force prefer to pass through ferromagnetic substance than through air ?

asked Jul 21, 2015 by meena.p

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Name the material used in making the core of moving coil galvanometer .

asked Jul 21, 2015 by meena.p

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An electron and a proton equal momenta, enter a uniform magnetic field at right angles to the field lines. What will be the ratio of the radii of an vature of there trajectories .

asked Jul 21, 2015 by meena.p

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The earth's field departs from its dipole shape substantially at large distance (greater than about 30,000 km) What agencies may be responsible for this distortion ?

asked Jul 21, 2015 by meena.p

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Why do we prefer steel or alnico for making permanent magnets ?

asked Jul 21, 2015 by meena.p

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A magnetic needle of magnetic moment $4.8 \times 10^{-2}\;JT^{-1}$ is placed at $30^{\circ}$ with the direction of uniform magnetic field of magnitude $3 \times 10^{-2} \;T$ Calculate the torque acting on the needle

asked Jul 21, 2015 by meena.p

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A magnetized needle is placed $30^{\circ}$ with direction of uniform magnetic field of intensity $3 \times 10^{-2}\;T$ The torque acting on the needle is $7.2 \times 10^{-4} \;J$ Calculate the magnetic moment of the needle .

asked Jul 20, 2015 by meena.p

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The vertical component of earth magnetic field at a plane is $\large\frac{1}{\sqrt 3}$ times the horizontal component. What is the value of angle of dip at this place ?

asked Jul 20, 2015 by meena.p

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A magnetic needle of a magnetic moment $60 Am^2$ is placed at a place . The needle points towards the geographical north. using the data given below, find the value of declination at the point . Horizontal component of earth magnetic field $=40 \times 10^{-6}wb m^{-2}$ and torque experienced by the needle $=1.2 \times 10^{-3}Nm$

asked Jul 20, 2015 by meena.p

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What is the SI unit for magnet flux and magnetic field strength

asked Jul 20, 2015 by meena.p

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What is the $SI$ unit of pole strength ?

asked Jul 20, 2015 by meena.p

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Name any two dia magnetic substance

asked Jul 20, 2015 by meena.p

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State tangent law in magnetism.

asked Jul 20, 2015 by meena.p

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What is the reduction factor of galvanometer . The amount of of current required to produce $45^{\circ}$ deflection in a galvanometer is defined as it reduction factor.

asked Jul 20, 2015 by meena.p

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How does the magnetic moment of each part of the bar magnet . change if it is cut into two equal pieces along its length ?

asked Jul 20, 2015 by meena.p

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How does the pole strength of each part of bar magnet change if it is cut into equal piece along its length ?

asked Jul 20, 2015 by meena.p

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How does the magnetic moment of each part of the bar magnet change it is cut into two equal piece transverse to its length ?

asked Jul 20, 2015 by meena.p

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How does the pole strength of each part of a bar magnet change if it is cut into two equal pieces transverse to its length ?

asked Jul 20, 2015 by meena.p

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Where on the earth's surface is the value of angle of dip maximum ?

asked Jul 20, 2015 by meena.p

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What is the value of the horizontal component of the earth 's magnetic field at magnetic poles?

asked Jul 20, 2015 by meena.p

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There are two current planer coils made each from identical wires of length L. $C_1$ is circular coil (radius R) and $C_2$ is square (side a). They are so constructed that they have same frequency of oscillation when they are placed in the same uniform magnetic field B and carry same current. Find a in term of R.

asked Jul 20, 2015 by meena.p

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Consider the plane S formed by the dipole axis and the axis of earth . Let P be point of intersection of the geographical and magnetic equators. Obtain the declination and dip angles at P and Q.

asked Jul 16, 2015 by meena.p

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Assume the dipole model for earth's magnetic field B which is given by $B_v$ =Vertical component of magnetic field $=\large\frac{\mu_0}{4 \pi}.\frac{2m \cos \theta}{r}$ $B_H$= Horizontal component of magnetic field $\qquad= \large\frac{\mu_o}{4 \pi} \frac{\sin \theta m}{r^3}$ $\theta= 90^{\circ}$- latitude as measured from magnetic equator . Find loci of points for which dip angle is $\pm 45^{\circ}$

asked Jul 16, 2015 by meena.p

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Assume the dipole model for earth's magnetic field B which is given by $B_v$ =Vertical component of magnetic field $=\large\frac{\mu_0}{4 \pi}.\frac{2m \cos \theta}{r}$ $B_H$= Horizontal component of magnetic field $\qquad= \large\frac{\mu_o}{4 \pi} \frac{\sin \theta m}{r^3}$ $\theta= 90^{\circ}$- latitude as measured from magnetic equator . Find loci of points for which clip angle is zero.

asked Jul 16, 2015 by meena.p

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Assume the dipole model for earth's magnetic field B which is given by $B_v$ =Vertical component of magnetic field $=\large\frac{\mu_0}{4 \pi}.\frac{2m \cos \theta}{r}$ $B_H$= Horizontal component of magnetic field $\qquad= \large\frac{\mu_o}{4 \pi} \frac{\sin \theta m}{r^3}$ $\theta= 90^{\circ}$- latitude as measured from magnetic equator . Find loci of points for which $|B|$ is minimum

asked Jul 16, 2015 by meena.p

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A bar magnet of magnetic m and moment of inertia I (about center , perpendicular to length ) is cut into two equal pieces, perpendicular to length . Let T be the period of oscillations of the original magnet about an axis . through the mid -point , perpendicular to length , in a magnetic field B. What would be the similar period $T^1$ for each piece?

asked Jul 16, 2015 by meena.p

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A proton has spin and magnetic moment just line an electron , Why then its effect is neglected in magnetism of materials?

asked Jul 16, 2015 by meena.p

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A magnetic moment $\mu _s$ and $\mu_i$ associated with the intrinsic spin angular momentum $S$ and orbital momentum l respectively , of an electron are predicted by quantum theory (and verified experimentally to a high accuracy ) to be given by $\mu_s= -\bigg(\large\frac{e}{m} \bigg)$$s; \mu_e =-\bigg(\large\frac{e}{2m}\bigg)$$l$ Which of these relations is in accordance with the result expected classically ? outline the deviation of the classical result ?

asked Jul 16, 2015 by meena.p

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A rowland ring of mean radius $15\;cm$ has $3500$ turns of wire wound on a ferro magnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetizing current of $12.A$?

asked Jul 15, 2015 by meena.p

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A sample of paramagnetic salt contains $2.0 \times 10^{24} $ atomic dipoles each of dipole moment $1.5 \times 10^{-23}\; J/T$. the sample is placed under a homogeneous magnetic field of $0.64 \;T$ and colled to a temperature of $4.2 \;K$ . The degree of magnetic saturation achieved is equal to $15\%$ What is the total dipole moment of the sample for a magnetic field of $0.98 \;T$ and a temperature of $2.8 \;k$? (assume curies's law)

asked Jul 15, 2015 by meena.p

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A mono energetic $(18\;kev)$ electron beam initially in the horizontal direction is subjected to a horizontal magnetic field of $0.4\;G$ normal to the initial direction . Estimate the up or down deflection of the beam over a distance of $30\;cm(m_e=9.11 \times 10^{-19}\;c)$

asked Jul 15, 2015 by meena.p

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A magnetic dipole is under the influence of two magnetic fields. The angle between the field direction is $60^{\circ}$ and one of the field has a magnitude of $1.2 \times 10^{-2}\;T$ If the dipole comes to stable equilibrium to an angle of $15^{\circ}$ with this field , What is the magnitude of the other field ?

asked Jul 15, 2015 by meena.p

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The current in the coil is reversed and the coil is rotated about its vertical axis by an angle of $90^{\circ}$ in the anti clock wise sense looking from above . Predict the direction of the needle. Take the negative declination at the places to be zero.

asked Jul 15, 2015 by meena.p

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A compass needle free to turn in a horizontal plane is placed at the center of circulaum coil of $30$ turns and radius $12\;cm$ . The coil is in a vertical plane making an angle of $45^{\circ}$ with the magnetic medician. when the current in the coil is $0.35\;A$ the needle points west to East. Determine the horizontal component of the earth's magnetic field at the location .

asked Jul 15, 2015 by meena.p

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A telephone cable at a place has four long straight horizontal wires carrying a current of $1.0 \;A$ in the same direction east to west. The earth magnetic field at the place is $ 0.39 \;G$ and the angle of dip is $35^{\circ}$. The magnetic declination is nearly zero. what are the resultant magnetic fields at points $ 4.0 \;cm$ above the cable ?

asked Jul 15, 2015 by meena.p

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A telephone cable at a place has four long straight horizontal wires carrying a current of $1.0 \;A$ in the same direction east to west. The earth magnetic field at the place is $ 0.39 \;G$ and the angle of dip is $35^{\circ}$. The magnetic declination is nearly zero. what are the resultant magnetic fields at points $ 4.0 \;cm$ below the cable ?

asked Jul 15, 2015 by meena.p

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A long straight horizontal cable carries a current of $2.5 \;A$ in the direction $10^{\circ}$ south of went to $10^{\circ}$ north of east . The magnetic meridian of the place happens to be $10^{\circ}$ west of the geographic meridian . The earth's magnetic field at the location is $ 0.33 \;G$ and the angle of the dip is zero. Locate the line of neutral points (ignore the thickness of the cable ). (At neutral point magnetic field due to current - carrying cable is equal and opposite to the horizontal component of earth's magnetic field )

asked Jul 15, 2015 by meena.p

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A certain region of space is to be shielded from magnetic fields. Suggest a method.

asked Jul 14, 2015 by meena.p

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What kind of ferromagnetic material is used for coating magnetic tapes in casette player or for building memory stores in a modern computer ?

asked Jul 14, 2015 by meena.p

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A system displaying a hysteresis loop such as a ferromagnet, is a device for storing memory . explain the meaning of this statement.

asked Jul 14, 2015 by meena.p

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The hysteresis loop of a soft iron piece has a much smaller are than that of a carbon steel piece . If the material is to go through repeated cycle of magnetization , Which piece will dissipate greater heat energy ?

asked Jul 14, 2015 by meena.p

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Explain quantitative on the basis of domain picture the reversibility of a ferromagnet?

asked Jul 14, 2015 by meena.p

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Would the maximum possible magnetization of a para magnetic sample be of the same order of magnitude as the magnetization of a ferromagnet.

asked Jul 14, 2015 by meena.p

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If a torrid uses Bismuth for its core, will the field in the core be (slightly ) greater or (slightly ) less than when the core is empty ?

asked Jul 14, 2015 by meena.p

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Is the permeability of a ferromagnetic material independent of the magnetic field ? If not, is it more for lower or higher fields?

asked Jul 14, 2015 by meena.p

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Magnetic field lines are always nearly normal to the surface of a force magnet at every point. (This fact is analogous to the static electric field lines being normal to the surface of a conductor at every Point ) Why?

asked Jul 14, 2015 by meena.p

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Why is diamagnetism, in contract , almost independent of temperature ?

asked Jul 14, 2015 by meena.p

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Why does a para magnetic sample display greater magnetization (for the same magnetizing field) when colled ?

asked Jul 14, 2015 by meena.p

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A short bar magnet of magnetic moment $5.25 \times 10^{-2}\;J/T$ is placed with its axis perpendicular to the earth's field direction . At what distance from the center of the magnet , the resultant field is inclined at $45^{\circ}$ with earth's field at the place is given to be $0.42\;G$ Ignore the length of the magnet in companion to the distance involved

asked Jul 14, 2015 by meena.p

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