∮ B → · d s → = 0 equation is not according to the following

The number of magnetic lines leaving a surface is not equal to that of entering the surface.

The net magnetic flux enclosed by any closed surface is zero.

No isolated magnetic poles are available.

The magnetic flux is positive at some place and it is negative at some other place.

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Earn 100

State Gauss' law for magnetism.

Important Questions on Magnetism and Matter

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

Why can't two magnetic field lines intersect?

MEDIUM

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

An insulating thin rod of length

l

has a linear charge density

ρ (x) = ρ_{0} \frac{x}{l}

on it. The rod is rotated about an axis passing through the origin

(x = 0)

and perpendicular to the rod. If the rod makes

n

rotations per second, then the time averaged magnetic moment of the rod is:

HARD

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

The magnetic flux near the axis and inside the air-core solenoid of length

60 cm

carrying current

I

1.57 \times 10^{6} Wb .

Its magnetic moment will be (cross-sectional area of a solenoid is very small as compared to its length,

μ_{0} = 4 π \times 10^{- 7}

SI units)

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

The magnetic dipole moment of a short magnetic dipole at a distant point along the equator of magnet has a magnitude of

X

in SI units. If the distance between point and the magnet is halved then the magnitude of dipole moment will be

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

State Gauss Law for Magnetism.

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

The magnetization of bar magnet of length

5 cm

, cross-sectional area

2 {cm}^{2}

and net magnetic moment

1 A m^{2}

HARD

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

Two short bar magnets of length

1 cm

each have magnetic moments

1 .20 A m^{2}

and

1 .00 A m^{2}

respectively. They are placed on a horizontal table parallel to each other with their

N

poles pointing towards the south. They have a common magnetic equator and are separated by a distance of

20 .0 cm

. The value of the resultant horizontal magnetic induction at the mid-point

O

of the line joining their centres is close to
( Horizontal component of earth's magnetic induction is

3 .6 \times 10^{- 5} Wb m^{- 2}

)

MEDIUM

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

An electron is moving along

+ x

direction with a velocity of

6 \times 10^{6} {ms}^{- 1}

. It enters a region of uniform electric field of

300 V / c m

pointing along

+ y

direction. The magnitude and direction of the magnetic field set up in this region such that the electron keeps moving along the x direction will be:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

The net magnetic flux through any closed surface is:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

_____ Law of magnetism establishes that monopoles do not exist.

HARD

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

An electron gun is placed inside a long solenoid of radius

R

on its axis. The solenoid has

n

turns/length and carries a current

I .

The electron gun shoots an electron along the radius of the solenoid with speed

v .

If the electron does not hit the surface of the solenoid, maximum possible value of

v

is (all symbols have their standard meaning):

Question Image

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

State Gauss’ law for magnetism. Explain its significance.

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

In a permanent magnet at room temperature

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

A circular coil having

N

turns and radius

r

carries a current

I .

It is held in the

X Z

plane in a magnetic field

B \hat{i}

. The torque on the coil due to the magnetic field is:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

A small bar magnet is placed with its axis at

30^{o}

with an external magnetic field of

0.06 T

experiences a torque of

0.018 Nm

. The minimum work required to rotate it from its stable to unstable equilibrium position is:

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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

Inside a bar magnet, the magnetic lines of force

MEDIUM

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

A thin rod of length

L

is magnetized and has magnetic moment

M

. The rod is then bent in a semicircular arc. The magnetic moment in the new shape is

HARD

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

A hoop and a solid cylinder of same mass and radius are made of a permanent magnetic material with their respective axes. But the magnetic moment of hoop is twice of solid cylinder. They are placed in a uniform magnetic field in such a manner that their magnetic moments make a small angle with the field. If the oscillation periods of hoop and cylinder are

T_{h}

and

T_{c}

respectively, then:

EASY

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

State Gauss

'

s law of magnetism. Explain its significance

MEDIUM

Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

\oint \vec{B} \cdot d \vec{s} = 0

equation is not according to the following

State Gauss' law for magnetism.

Important Questions on Magnetism and Matter

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