The \(B\text{-}H\) curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solenoid with \(1000~ \text{turns/cm.}\) The current that should be passed in the solenoid to demagnetise the ferromagnet completely is :

1. \(2~\text{mA}\)
2. \(20~\mu\text{A}\)
3. \(1~\text{mA}\)
4. \(40~\mu\text{A}\)
Subtopic:  Magnetic Materials |
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Magnetic materials used for making permanent magnets (\(\text{P}\)) and magnets in a transformer (\(\text{T}\)) have different properties of the following, which property best matches for the type of magnet required?

1. \(\text{T}\) : Large retentivity, small coercivity
2. \(\text{P}\) : Small retentivity, large coercivity
3. \(\text{T}\) : Large retentivity, large coercivity
4. \(\text{P}\) : Large retentivity, large coercivity

Subtopic:  Magnetic Materials |
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A perfectly diamagnetic sphere has a small spherical cavity at its centre, which is filled with a paramagnetic substance. The whole system is placed in a uniform magnetic field \(\vec{B}\). Then the field inside the paramagnetic substance is:

   

1. Zero 
2. \(\vec{B}\)
3. much larger than \(|\vec{B}|\) and parallel to \(\vec{B}\)  
4. much larger than \(|\vec{B}|\) and opposite to \(\vec{B}\) 

Subtopic:  Magnetic Materials |
From NCERT
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A soft ferromagnetic material is placed in an external magnetic field. The magnetic domains:

1. increase in size but no change in orientation
2. have no relation with an external magnetic field
3. decrease in size and change its orientation
4. may increase or decrease in size and change its orientation

Subtopic:  Magnetic Materials |
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In a ferromagnetic material, below the curie temperature, a domain is defined as:

1. a macroscopic region with zero magnetization.
2. a macroscopic region with consecutive magnetic dipoles oriented in opposite directions.
3. a macroscopic region with randomly oriented magnetic dipoles.
4. a macroscopic region with saturation magnetization.
Subtopic:  Magnetic Materials |
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The susceptibility of a paramagnetic material is \(99.\) The permeability of the material in Wb/A-m is: 
(Permeability of free space, \(\mu_{0}=4\pi \times 10^{-7}\) Wb/A-m )
1. \(4 \pi \times 10^{-7} \)
2. \( 4 \pi \times 10^{-4} \)
3. \( 4 \pi \times 10^{-5} \)
4. \( 4 \pi \times 10^{-6}\)
Subtopic:  Magnetic Materials |
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Given below two statements:
Statement I:  For diamagnetic substances, \(-1 \leq \chi <0 ,\) where \(\chi\) is the magnetic susceptibility.
 
Statement II: Diamagnetic substances, when placed in an external magnetic field, tend to move from the stronger to the weaker part of the field.
 
1. Both Statement I and Statement II are correct.
2. Both Statement I and Statement II are incorrect.
3. Statement I is correct, and Statement II is incorrect.
4. Statement I is incorrect, and Statement II is correct.
Subtopic:  Magnetic Materials |
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Match List-I with List-II
List - I List - II
A \(Y= \)magnetic susceptibility
\(X=\) magnetizing field
I
B \(Y= \) magnetic field
\(X=\) distance from centre of a current carrying wire for \(x<a\) (where \(a=\) radius of wire)
II
C \(Y= \) magnetic field
\(X=\) distance from centre of a current carrying wire for \(x>a\) (where \(a=\) radius of wire)
III
D \(Y= \) magnetic field inside solenoid
\(X=\) distance from centre
IV
 
Choose the correct answer from the options given below :
1. (A)-(III), (B)-(I), (C)-(IV), (D)-(II)
2. (A)-(III), (B)-(IV), (C)-(I), (D)-(II)
3. (A)-(I), (B)-(III), (C)-(II), (D)-(IV)
4. (A)-(IV), (B)-(I), (C)-(III), (D)-(II)
Subtopic:  Magnetic Materials |
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Paramagnetic substances:
A. align themselves along the directions of external magnetic field.
B. attract strongly towards external magnetic field.
C. has susceptibility little more than zero.
D. move from a region of strong magnetic field to weak magnetic field.

Choose the most appropriate answer from the options given below:
1. A, C only
2. B, D only
3. A, B, C, D
4. A, B, C only
Subtopic:  Magnetic Materials |
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