Tag: physics

Questions Related to physics

Which of the following is true regarding dimagnetic substances (symbols have their usual meaning)?

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. ${ \mu } _{ r }>1,{ \chi } _{ m }>1$

  2. ${ \mu } _{ r }>1,{ \chi } _{ m }<1$

  3. ${ \mu } _{ r }<1,{ \chi } _{ m }<0$

  4. ${ \mu } _{ r }<1,{ \chi } _{ m }>0$

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Correct Option: C
Explanation:

Diamagnetic substances induce magnetic field in the direction opposite to an external applied magnetic field and thus are repelled by external applied magnetic field.

Magnetic susceptibility of these substances is very small and negative    i.e    $\chi _m  < 0$ 
For example:
For silicon, $\chi _m =  -4.2 \times 10^{-6}$
From the equation, $\mu _r = 1+ \chi _m$
Thus, $\chi _m<0$ $\implies  \mu _r  <1$    
Hence, such materials have magnetic permeability less than unity.

Susceptibility is small and negative for

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. para magnetic

  2. diamagnetic

  3. ferro magnetic

  4. electromagnetic

Show answer
Correct Option: B
Explanation:

diamagnetic
$-1 \leq x < 0$
$\chi =susceptibility$

Susceptibility is small and positive for

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. para magnetic only

  2. diamagnetic only

  3. ferro magnetic only

  4. Both 1 & 3

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Correct Option: A
Explanation:

Paramagnetic material $0< \chi < \varepsilon $
$\varepsilon $ it small, positive and less than one.
$\chi $ is suscepticity

Susceptibility is large and positive for

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. para magnetic

  2. diamagnetic

  3. ferro magnetic

  4. electromagnetic

Show answer
Correct Option: C
Explanation:

Diamagnetic          Paramagnetic             ferromagnetic
-1 $\leq$ $\chi$ < 0            0 < $\chi$ < $\varepsilon$                 $\chi$ >>1
$\chi $$=$magnetic susceptibility

The core of electromagnet is made of soft iron, because
a) susceptibility of soft iron is very high
b) coercivity of soft iron is very low

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. only a is correct

  2. only b is correct

  3. both a and b are correct

  4. both a and b are wrong

Show answer
Correct Option: C
Explanation:
Because the suceptibility of the soft iron is very high. and its coercivity is very low,it is very less corrosive. 
$\chi$ >> 1 (Because it is a ferromagnetic substance.)

The value of susceptibility for super conductor is

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. 0

  2. $\infty $

  3. +1

  4. -1

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Correct Option: D
Explanation:

-1, Because superconductor are perfect diamagnetic substances.

Susceptibility is positive and large for a

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. paramagnetic substance

  2. ferromagntic substance

  3. diamagnetic substance

  4. non magnetic substance

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Correct Option: B
Explanation:

For ferromagnetic substances, $\chi _m$ is large and positive.

A superconductor exhibits perfect:

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. ferrimagnetism

  2. ferromagnetis

  3. paramagnetism

  4. diamagnetism

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Correct Option: D
Explanation:

A superconductor exhibits perfect diamagnetism.

The magnetic materials having negative magnetic susceptibility are

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. non-magnetic

  2. para magnetic

  3. dia magnetic

  4. ferro magnetic

Show answer
Correct Option: C
Explanation:

Magnetic susceptibility is a dimensionless proportionality constant that indicates the degree of magnetisation of a material in response to an applied magnetic field.

Substances such as copper, iron have negative susceptibility as these substances are diamagnetic substances.
Substances with negative susceptibility signifies that they are repelled by magnets.

Which of the following group is diamagnetic?

physics magnetism and matter magnetic materials behaviour of substances in magnetic field classification of magnetic materials

  1. Copper, hydrogen, silver

  2. Copper, hydrogen, argon

  3. Hydrogen, oxygen, argon

  4. Copper, silver, oxygen

Show answer
Correct Option: A
Explanation:

Diamagnetic substances are those which are freebly repelled by the magnetic field.
$\therefore$ Copper, Hydrogen, Silver are diamagnetic as their atoms have net magnetic dipole moment zero.