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Syllabus

Define magnetic elements of earth?

Please answer urgently :

26.The following figure shows the variation of intensity of magnetisation versus the applied magnetic field intensity, Hj for two magnetic materials A and B:

(a) Identify the materials A and B.

(b) Why does the material B have a larger susceptibility than A for a given field at constant temperature?

WAT IS RETENTIVITY AND COERCIVITY

REPLY AS FAST AS POSSIBLE

what is the principle of moving coil galvanometer?

what is the si unit of permeability. what do Tm/A stands for?

Why do magnetic field lines always form closed loops?

(1) $\frac{{\mu}_{0}}{4\pi}\xb7\frac{M}{{d}^{3}}$ (2) $\frac{{\displaystyle {\mu}_{0}}}{{\displaystyle 4\pi}}\xb7\frac{{\displaystyle 2M}}{{\displaystyle {d}^{3}}}$ (3) $\frac{{\displaystyle {\mu}_{0}}}{{\displaystyle 4\pi}}\xb7\frac{{\displaystyle 2\sqrt{2}M}}{{\displaystyle {d}^{3}}}$ (4) Zero

A 2MeV proton is moving perpendicular to a uniform magnetic field of 2.5 Tesla the force on the proton is ?

ans.. 16F

what is difference between diamagnetic paramagnetic and ferromagnetic?atleast 10 points.

the critical angle for glass air interface is ic. will the critical angle for glass water interface be greater than or less than ic ? why?

what are eddy currents and its applications???

The susceptibility of a magnetic material is 0.9853. Identify the type of the magnetic material.Draw the modification of field pattern on keeping piece of this material in a uniform magnetic field.

a bar magnet is stationary in magnetic meridian. a similar magnet is kept parallel to it such that their centres lie on their perpendicular bisectors, if the second magnet is free to move then what type of motion will it have....translatory, rotatory or both and why???

Derive expression for magnetic dipole moment of an electron revolving around a nucleus

^{0 }, then how many oscillations per min will this needle perform in vertical north-south plane and in vertical east-west plane?Give 5 differences between a bar magnet and a solenoid with their diagrams?

why is calcium listed as paramagnetic even though it has no unpaired electron ??

a jet plane is travelling west at 450 ms^{-1}. if the horizontal component of earth's magnetic field at that place is 4 * 10^{-4}Tesla and the angle of dip is 30 degrees, find the emf induced between the ends of the wings having span of 30 m.(1) Low hysteresis loss and low permeability

(2) Low hysteresis loss and high permeability

(3) High hysteresis loss and low permeability

(4) High hysteresis loss and high permeability

Sol. Answer (2) 3

What is benifit of high permeability of electrical machines

Working of Cyclotron?

Why is diamagnetism independent of temperature?

a) 2.4N

b) 1.2N

c) 0.6N

d) 0.3N

A thin bar magnet is cut into two equal parts.the ratio of moment of inertia to the magnetic moment of each part will become?(as compare to original magnet)

solution please.

options-1) 1/2

2)1/4

3)1/8

4)1

an element delta l=delta x l is placed at the origin and carriersa current I=2A.find out magnetic field at point P on y axis at distance of 1.0m due to element delta x=1cm.give also direction of field produced?

what do you mean by current sensitivity of a moving coil galvanometer ?on what factors does it depends?

The horizontal component of earth 's magnetic field at a place is B and angle of dip is 60 degrees. What is the value of vertical component of earth 's magnetic field at equator?

This question was asked in 2012 boards.I asked ths question yesterday also and the answer given by you is different from that available on this site where question-answers of previous year board papers are given.

there the answer is given to be zero and i don't undestand how. please review the question and explain how the vertical component of earth's magnetic field is zero at equator.

thank you

Horizontal component of earth's magnetic field at a place is root 3 times its vertical component . what is the value of angle of dip at the place ?

if a magnet is suspended at an angle 30 degree to the magnetic meridian the dip needle makes angle of 45 degree with the horizontal. the real dip is ??

^{-5}Wb in a bar of iron of cross section 0 .2 cm^{2}. Calculate the Permeability and Susceptibility of the bar ?dapart. If the length Of each magnet is negligible compared tod, the force between them will be inversely proportional to $1.{d}^{2}\phantom{\rule{0ex}{0ex}}2.d\phantom{\rule{0ex}{0ex}}3.{d}^{3}\phantom{\rule{0ex}{0ex}}4.{d}^{4}$

true value of dip at a place is 45 degree.the plane of the dip circle is turned through 60 degree from the magnetic meridian.find apparent value of dip?please explain me the question with the help of figure a and give its solution.

Two magnets of magnetic moments M and 3

^{1/2 }M are joined to form a cross. The combination is suspended in a uniform magnetic field B. The magnetic moment M now makes an angle θ with the field direction. find the value of angle θ.A magnetised needle in a uniform magnetic field experience a torque but no net force . An iron nail near a bar magnet however experience a force of attraction in addition to a torque . How??

why a galvanometer is not used to measure current in a given circuit?

a circular coil, of radius R, carries a current I. write the exxpression for the magnetic field due to this coil at its center. find out the direction of the magnetic field.

A wheel with 8 metallic spokes each 50cm long is rotated with a speed of 120rev./min . The earth's magnetic field at the place is 0.4G and the angle of dip is 60 . Calculate the emf induced between the axle and the rim of the wheel. How will the value of emf be affected if the number of spokes were increased ?

1) An electron and proton moving parallel to each other in the same direction with equal momentum enter into a uniform magnetic field which is at right angle to thier velocites trace their trajectories in the magnetic field.

two identical charged particles moving with same speed enter a region of uniform magnetic field. if one of these enters normal to the feild direction and the other along a direction at 30'c with the field , what would be the ratio of their angular frequencies?

in what respect is a toroid different from a solenoid ? draw and compare the pattern of magnetic field lines in the 2 cases

7. A cylinder of mass M and radius 2R has a groove of radius R. A block Of

mass m is hung from the circumference of the cylinder and the cylinder

itself is hung from a rigid support by a thread wound on the groove as

shown in the figure.

If the acceleration of centre of mass of the cylinder is 'a

_{1}' acceleration ofthe block is a

_{2}downward and angular acceleration of the cylinder is $\alpha $then relation between a

_{l}, a_{2}_{ }and $\alpha $ will be $\left(\mathrm{A}\right){\mathrm{a}}_{1}-\mathrm{\alpha R}={\mathrm{a}}_{2}\phantom{\rule{0ex}{0ex}}\left(\mathrm{B}\right){\mathrm{a}}_{1}-2\mathrm{\alpha R}={\mathrm{a}}_{2}\phantom{\rule{0ex}{0ex}}\left(\mathrm{C}\right){\mathrm{a}}_{1}+{\mathrm{a}}_{2}=\frac{\mathrm{\alpha R}}{2}\phantom{\rule{0ex}{0ex}}\left(\mathrm{D}\right){\mathrm{a}}_{1}-{\mathrm{a}}_{2}=3\mathrm{\alpha R}\phantom{\rule{0ex}{0ex}}$

Apparent dips when dip circle is placed in two mutually perpendicular directions are 30 and 45 degree.What is actual dip at that place???

20 Area of one side of each plate is A and separation between consecutive plates is d. Emf of the battery connected is V. The charge on plate 2 is .

$\left(1\right)\frac{A{\epsilon}_{0}V}{d}\left(2\right)\frac{-2A{\epsilon}_{0}V}{d}\left(3\right)\frac{-A{\epsilon}_{0}V}{d}\left(4\right)\frac{2A{\epsilon}_{0}V}{d}$

A rod of length L, along East-West direction is dropped from a height H.

if B be the magnetic field due to earth at that place and angle of dip isx, then what is the magnitude of induced emf across two ends of the rodwhen the rod reaches the earth?A charge Q moving in a straight line is accelerated by a potential difference V.it enter a uniform magnetic field B perpendicular to its path.

Deduse in terms of B an expearence radius of circular path which is travels

Q.3. A freely suspended magnet oscillates with period T in earth 's horizontal magnetic field. When a bar magnet is brought near it, such that the magnetic field created by bar magnet is in same direction as earth 's horizontal magnetic field, the period decreases to $\frac{T}{2}$. The ratio of the field of the magnet F to the earth's magnetic field (H) is

(a) 1 : 3

(b) 1 : 1

(c) 3 : 1

(d) 9 : 1

Sir,

rnA bar magnet is stationary in magnetic meridian. Another similar magnet is kept parallel to it,such that the centre lie on their perpendicular bisectors.If the second magnet is free to move, then what type of motion it will have : translatory , rotatory or both? Explain the answer please.

Write the expression for the magnetic moment due to a planar square loop of side ‘

l’ carrying a steady current I in a vector form.In the given figure this loop is placed in a horizontal plane near a long straight conductor carrying a steady current I

_{1}at a distancelas shown. Give reason to explain that the loop will experience a net force but no torque. Write the expression for this force acting on the loop.(1)the north pole of one faces the south pole of the other

(2)the north pole of one faces the north pole of the other

a magnetic needle free to rotate in a vertical plane, orients itself vertically at a certain place on earth. what are the values of horizontal component of earth's mag field and angle of dip at that place?

A dip ciccle shows an apparent dip of 60 degree at a place where the true dip is 45 degree. if the dip circle is rotated throgh 90 degree, what apparent dip will it show? first of all please tell me what is the meaing of apparent dip.how can a dip be apparent? it should always be true dip?

why does a freely suspended magnet always points along north- south direction. ?

Q. A particle of mass m is thrown horizontally from point P, as shown in the figure, with speed 5 m/s. It strikes an inclined plane perpendicularly as shown. The inclination of the plane is 30

^{o}with the horizontal. Then, the height h shown in the figure is (Take g= 10 m/s^{2})(A) 3.75m (B) 5.0m

(C) 4.75m (D) 0.417

A closely wound solenoid of 2000 turns and area of cross-section 1.6 × 10

^{−4}m^{2}, carrying a current of 4.0 A, is suspended through its centre allowing it to turn in a horizontal plane.(a) What is the magnetic moment associated with the solenoid?

(b) What is the force and torque on the solenoid if a uniform horizontal magnetic field of 7.5 × 10

^{−2}T is set up at an angle of 30º with the axis of the solenoid?$1)\frac{2{\mu}_{0}M}{4{\mathrm{\pi d}}^{3}}\phantom{\rule{0ex}{0ex}}2)\frac{{\mathrm{\mu}}_{0}\mathrm{M}}{4{\mathrm{\pi d}}^{3}}\phantom{\rule{0ex}{0ex}}3)\mathrm{Zero}\phantom{\rule{0ex}{0ex}}4)\frac{\sqrt{5}{\mathrm{\mu}}_{0}\mathrm{M}}{4{\mathrm{\pi d}}^{3}}$

A ball of mass m is tied with two strings of equal length on a rod !!! If the rod is rotated with angular velocity w ( omega ) , then ------(1) T1 = T2........(2) T2 is more than T1......(3) T1 is more than T2.......(4) T1 = T2 / 6 ..............(NOTE ----- T1 AND T2 ARE THE TENSIONS OF STRING 1 AND 2 RESPECTIVELY !!! ) KINDLY HELP !!!

Question No. 13

A pulse of light of duration 100 ns is absorbed completely by a small object initially at rest. Power of the pulse is 30 mW and the speed of light is 3 $\times {10}^{8}$ m/s. The final momentum of the object is

A. 0.3$\times {10}^{-17}kgm{s}^{-1}$

B. 1.0$\times {10}^{-17}kgm{s}^{-1}$

C. 3.0$\times {10}^{-17}kgm{s}^{-1}$

D. 9.0$\times {10}^{-17}kgm{s}^{-1}$

a coil of 40 ohm resistance, 100 turns and radius 6mm is connected to ammeter of resistance 160 ohm. coilis placed perpendicular to the magnetic field. when coil is taken out of the field 32 microcoulomb charge flows through it. the magnetic flux density is:

(A) Magnetic and electric field are uniform throughout region and do not vary with time

(B) Magnetic field is constant throughout region but vary with time and electric field is not constant throughout region and independent of time

(C) Magnetic field is not constant throughout region but independent of time and electric field is constant throughout region and vary with time

(D) Energy density (u) due to magnetic field varies with time as u = bt

^{2}. (Where b is positive constant)distinguish the magnetic properties of dia, para and ferromagnetic substances in term of,

(a) susceptibility

(b) magnetic permeability

(c) coercivity

Are the following topics included in the cbse class 12 physics portions or have they been deleted?

1)Magnetization and magnetic intensity

a)susceptibility

b)permeability

2)Hysteresis loop and retentivity

2)) along its length ????

What is Dip Circle? Explain its working.

(1) 2 V

(2) $\frac{V}{2}$

(3) 4 V

(4) V

(1) One

(2) Two

(3) Four

(4) Infinite

Sol. Answer (4)

Pls explain why

1. Give reason: electric lines of force do not form closed loop while magnetic field lines form closed loop.2. Why do like poles repel each other and unlike poles attract each pole ? Give satisfactory reason.Two short magnets P and Q are placed one over another with their magnetic axes mutually perpendicular to each other. It is found that resultant field at a point on the prolongation of the magnetic axes of P is inclined at 30 with this axis. Compare the magnetic moments of the tw magnets.