Very Short Question Answers

Q1. A magnet dipole placed in a magnetic field experiences a net force what can you say about the nature of themagnetic field?

Ans.

If a magnet dipole placed in a magnetic field experiences a net force the field may be non-uniform.

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Q2. What happens to compass needles at the earth’s poles?

Ans.

At the Earth’s poles, the compass needle can point along any direction, if the needle is only capable of  moving in horizontal plane as $B_{H} =0.$
(or)

At the Earth’s poles, the compass needle can point straight down,if the needle is moving in a vertical plane as $B_{H} =0.$

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Q3. What do you understand by the ‘magnetization’ of a sample?

Ans.

Magnetization(M), of a sample is defined as its net magnetic moment per unit volume.
                                 $$M = \frac {m_{net}}{V  }      $$

    Unit∶$ A\,m^{-1}$

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Q4. What is the magnetic moment associated with a solenoid?

Ans.

Magnetic moment of a solenoid is $M=n\,i\,A=n\,i\,(\pi r^{2})$
   n =number of turns, I = current, A = area of cross section.

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Q5. What are units of magnetic moment, magnetic induction and magnetic field?

Ans.

Magnetic moment $(M): Am^{2}  $(or) $joule/tesla$
Magnetic induction$ (B):\: Tesla\, (or)\: wb/m^2$
Magnetic field strength $(H):Am^{-1}$

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Q6. Magnetic lines form continuous closed loops. Why?

Ans.

The magnetic lines of a magnet form continuous closed loops, because the magnetic poles north and south always exists together in pairs. (or) magnetic lines form continuous closed loops. Because magnetic monopoles do not exist.

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Q7. Define magnetic declination

Ans.

The angle between the geographic north and north shown by compass needle is called magnetic declination 
(or) The angle between the geographical meridian and magnetic meridian of the earth is called magnetic declination.

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Q8. Define magnetic inclination or angle of dip.

Ans.

The angle between horizontal to earth surface and net magnetic field of the earth BE at that point is called “angle of Dip”. 
(or) Angle of dip or magnetic inclination is the angle that the total magnetic field BE of the earth makes the surface of the earth.

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Q9. Classify the following materials with regard to magnetism: manganese, cobalt, nickel, bismuth, oxygen, copper

Ans.

Diamagnetic	Para magnetic	Ferro magnetic
Bismuth, copper	Manganese, oxygen	Nickel, cobalt

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Q10.  Define Curie temperature.

Ans.

The temperature of transition from ferromagnetic to paramagnetic is called the Curie temperature.

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Q11. State Gauss Law for Magnetism.

Ans.

The Net magnetic flux through any closed surface is Zero.

$$ \phi_{B}=\oint B.ds =0$$

 

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Q12. Which needle to be used at poles

Ans.

  Dip needle

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