Tag: magnetism

Questions Related to magnetism

How will you quantize the relative permeability of a paramagnetic substance ?

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Much more than one

  2. Slightly more than one

  3. Less than one but greater than zero

  4. Zero

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Correct Option: B
Explanation:

Paramagnetic substances are those which are attracted slightly in the direction of the magnetic field. As such, the magnetic permeability of these materials is slightly greater than $1$. 
Similarly, diamagnetic materials are those which are repelled slightly away from the direction of magnetic field. These materials have their permeability slightly less than $1$.
And ferromagnetic materials are those which are attracted very strongly and their permeabilities are much higher than $1$.

Some metals get magnetised by orientation of atomic magnetic moments in external magnetic field. What are they called ?

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. just magnets

  2. Paramagnetics

  3. dimagnetics

  4. ferromagnetic

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Correct Option: B

The relative permeability is represented by $\mu _r$ and the susceptibility by $\chi$ for a magnetic substance. Then, for a paramagnetic substance. Then, for a paramagnetic substance 

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. $\mu _r> 1, \chi >0$

  2. $\mu _r> 1, \chi < 0$

  3. $\mu _r > 1, \chi >0$

  4. $\mu _r < 1, \chi < 0$

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Correct Option: A
Explanation:

Susceptence $(\chi) = \dfrac{B-B _0}{B _0}$


Where $B _0$ is external applied magnetic field and $B$ is magnetic field in presence of paramagnetic substance.
Since dipoles in paramagnetic substance align in direction of applied magnetic filed, therefore $B > B _0$

And $B$ is bit more than $B _0$
$\Rightarrow \chi > 0$

And also $\mu _r = \chi + 1$
$\Rightarrow \mu _r  > 0 + 1$
$ \Rightarrow \mu _r > 1$
Therefore option A is correct.

Atomic number of an element is $26$. The element shows 

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Ferromagnetism

  2. Diamagnetism

  3. Paramagnetism

  4. None of these

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Correct Option: B

Consider the following statements and select the select option which correctly identifies true (T) and false (F).

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Iron loses its magnetism easily.

  2. Steel is a hard magnetic material.

  3. Soft iron is used to make permanent magnet.

  4. non of these

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Correct Option: A

According to  molecular orbital theory, the paramagnetism of $O _{2}$  molecule is due to presence of 

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. Unpaired electrons in the bonding $\sigma $ molecular orbital

  2. Unpaired electrons in the anti- bonding $\sigma $ molecular orbital

  3. Unpaired electron in the bonding $\pi $ molecular orbital

  4. Unpaired electrons in the anti - bonding $\pi $ molecular obrital

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Correct Option: A

Which of the following is paramagnetic  in nature ? 

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. $N _{2}$

  2. $C _{2}$

  3. $B _{2}$

  4. $O _{2}^{2+}$

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Correct Option: A

Substances in which the magnetic moment of a

single atom is not-zero

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. diamagnetic

  2. ferromagnetic

  3. paramagnetic

  4. electromagnetic

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Correct Option: C

An atom is paramagnetic if it has :

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. an electric dipole moment

  2. no magnetic moment

  3. a magnetic moment

  4. no electric dipole moment

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Correct Option: A

A paramagnetic substance when placed in an externally applied non-uniform magnetic field tends to ___________.

physics magnetism and matter paramagnetic material classification of magnetic material magnetism

  1. increase the applied field

  2. decrease the applied field

  3. vary the applied field

  4. change the applied field

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Correct Option: A
Explanation:

Paramagnetic substances are the substances which are feebly attracted by a magnet. When a non-uniform external magnetic field is applied to a paramagnetic substance the magnetic field tries to aligned the magnetic moment in the direction of the field 

Completely alignment is however not possible, on account of thermal vibration. A better allingement can be achieved by increasing the strength of the applied magnetic field.