Earth's magnetic field may be imagined to be due to a small bar magnet located at the centre of the earth. If the magnetic field at a point on the magnetic equator is 0 . 3 × 10 - 4 T , what is the moment of such a bar magnet? What is the value of the magnetic field at the north pole? (radius of the earth = 6 . 4 × 10 6 m )

Given that magnetic field at equator is = 0 . 3 × 10 - 4 T , radius of earth is 6 . 4 × 10 6 m Magnetic moment of such bar magnet is , B = μ 2 M 4 π r 3 Where r is radius of earth, M is moment of bar magnet and B is magnetic field 0 . 3 × 10 - 4 = 10 - 7 × 2 × M 6 . 4 × 10 6 3 M = 7 . 86 × 10 22 A m 2 Also magnetic field at north pole, B = μ 2 M 4 π R 3 B = 0 . 6 × 10 - 4 T

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Two bar magnets are bound together side by side and suspended, so as to swing in the horizontal plane. The combination makes one oscillation is $125,$ when like poles are together and $16$ seconds when the direction one of the magnet is reversed. Compare their magnetic moments.

Important Questions on Properties of Magnets and Terrestrial Magnetism

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 5

A compass needle makes

30

oscillations per minute in the earth's field. When a bar magnet is placed near it so as not to alter the direction of the needle, it makes

40

oscillations in one minute. How many times will the needle oscillate per minute if the magnet is reversed ?

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 6

At a place, where the true dip is

45 °,

the apparent dip is

60 ° .

In a plane perpendicular to the previous plane, what would be the apparent dip ?

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 7

At a place, the horizontal component of earth's magnetic field is

0.4212 \times 10^{- 4} T,

dip is

70 °

and declination is

15 ° .

What will be the horizontal and vertical components of earth's magnetic field in the geographical meridian there ?

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 8

Earth's magnetic field may be imagined to be due to a small bar magnet located at the centre of the earth. If the magnetic field at a point on the magnetic equator is $0.3 \times 10^{- 4} T,$ what is the moment of such a bar magnet? What is the value of the magnetic field at the north pole? (radius of the earth $= 6.4 \times 10^{6} m$ )

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 9

A magnetic needle of mass

8 gm

has a magnetic moment of

0.049 {Am}^{2} .

If the needle is to be maintained horizontal in the northern hemisphere, where should the point of support lie relative to its centre of gravity? The vertical component of earth's magnetic field is

0.2 \times 10^{- 4} T .

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 10

A B C D

is a table of sides

50 cm

each and

C

is towards magnetic north of

A

. At the corners

B

and

D

two identical short bar magnets are placed with their $S$ -pole towards

C

. Magnetic field at

C

is zero. Find the magnetic moment of each magnet. Given : horizontal component of earth's magnetic field is

0.4 \times 10^{- 4} T .

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12th West Bengal Board

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 11

A magnet is suspended horizontally in the magnetic meridian from its

cg .

By fine untwisted wire. When the upper end of the wire is twisted through

50 °

, the magnet is deflected by

5 ° .

Find the angle through which the upper end must be twisted in order that the magnet gets deflected by

10 °

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12th West Bengal Board

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 7 - Properties of Magnets and Terrestrial Magnetism>EXERCISE 7>Q 12

Find the magnetic moment of the magnet if the earth's horizontal magnetic field is $20 μ T .$

The needle of a deflection magnetometer deflects through $45 °$ from north-south when the instrument is used in Tan-A position with a magnet of length $8 cm$ placed at a distance of $20 cm$

Two bar magnets are bound together side by side and suspended, so as to swing in the horizontal plane. The combination makes one oscillation is 125, when like poles are together and 16 seconds when the direction one of the magnet is reversed. Compare their magnetic moments.

Important Questions on Properties of Magnets and Terrestrial Magnetism

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Two bar magnets are bound together side by side and suspended, so as to swing in the horizontal plane. The combination makes one oscillation is $125,$ when like poles are together and $16$ seconds when the direction one of the magnet is reversed. Compare their magnetic moments.