Tag: magnetism

Quizzes (14) Questions (113)

Questions Related to magnetism

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

When the atomic magnetic moments are randomly oriented in a solid its magnetic behavior is termed as

  1. semi-magnetic.

  2. anti-ferromagnetic.

  3. paramagnetic.

  4. poly crystalline.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

When the atomic magnetic moments are randomly oriented in a solid its magnetic behavior is termed as paramagnetic.in paramagnetism electrons are unpaired.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

Liquid oxygen remains suspended between two pole forces of a magnet because it is:

  1. diamagnetic

  2. paramagnetic

  3. ferromagnetic

  4. antiferromagnetic
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Oxygen is paramagnetic in nature. So if it will be attracted both by North pole or South pole. When it is placed exactly between two magnetic poles, the forces acting on it due to magnetic poles will be equal & opposite. Hence it will remain suspended between them.

Multiple choice physics magnetism and matter paramagnetic material classification of magnetic material magnetism

A substance is placed in a non uniform magnetic field. It experiences weak force towards the strong field. The substance is _________ type.

  1. Ferromagnetic

  2. Diamagnetic

  3. Paramagnetic

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Paramagnetic substance has the property that when they are placed in an external magnetic field, they get weakly magnetised in the same direction as that of external magnetic field and are weakly attracted by the external magnetic field.
So, correct answer is option C.

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

Magnetic induction due to a short bar magnet on its axial line is inversely proportional to cube of distance of the point.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Magnetic induction due to a short bar magnet on its axial line,

$B=\dfrac{\mu _0 M}{4\pi d^3}$
Magnetic induction due to a short bar magnet on its axial line is inversely proportional to cube of distance of the point.
$B\propto\dfrac{1}{d^3}$

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

The magnetic induction due to short bar magnet on its axial line at a distance 'd' is 'B'. What is the magnetic induction due to the same bar magnet on the same line at a distance $\displaystyle \frac{d}{4}?$

  1. 16B

  2. 32B

  3. 64B

  4. 128B
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$B \displaystyle = \frac{\mu _0  2M}{4 \pi  d^3}$
At $\displaystyle \frac{d}{4} $ distance,
$B' \displaystyle = \frac{\mu _0 2M}{4 \pi (d/4)^3}$
$\displaystyle = \frac{\mu _0  2M}{4 \pi d^3} \times 64 = 64 B$

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

If r be the distance of a point on the axis of a bar magnet from its centre, the magnetic field at this point is proportional to :

  1. (1/r)

  2. (1/r$^2$)

  3. (1/r$^3$)

  4. (1/r$^5$)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

For a short Bar Magnet, the magnetic induction at a point on the axix at a distance $r$ from centre is given by  the formula

$B = $   $(\dfrac{\mu _0}{4\pi} )\dfrac{2M}{r^3}$

$\Rightarrow$ $B= \dfrac{K}{r^3}$

$\Rightarrow$ $B\propto \dfrac{1}{r^3}$
Therefore, C is correct option.

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A bar magnet of magnetic moment 'M' has a magnetic length '2d'. Find magnetic induction on its equatorial line at a distance $'\sqrt{13 d}'$.

  1. <span>$\displaystyle \frac{\mu _0 M}{4 \pi (d^3)(17)^{\frac{3}{2}}}$</span>

  2. <span>$\displaystyle \frac{2\mu _0 M}{4 \pi (d^3)(17)^{\frac{3}{2}}}$</span>

  3. <span>$\displaystyle \frac{4\mu _0 M}{4 \pi (d^3)(17)^{\frac{3}{2}}}$</span>

  4. <span>$\displaystyle \frac{8\mu _0 M}{4 \pi (d^3)(17)^{\frac{3}{2}}}$</span>
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$r = \sqrt{13} d ;  2l  = 2d$
$B _eq = \displaystyle \frac{\mu _0}{4 \pi} \times \frac{\mu}{(r^2 + 1^2)^{\frac{3}{2}}}$
$\displaystyle =\frac{\mu _0}{4\pi} \times \frac{M}{\left ((\sqrt{13}d)^2 + (2d)^2 \right )^{\frac{3}{2}}}$
$=\displaystyle \frac{\mu _0}{4\pi} \times \frac{M}{(17 d^2)^{\frac{3}{2}}} = \frac{\mu _0 M}{4 \pi (d^3)(17)^{\frac{3}{2}}}$

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

If ratio of magnetic induction on the axial line of a long magnet at distance 20 cm and 30 cm is 128 : 27. Find length of the magnet.

  1. $ 10cm $

  2. <span>$ 20cm $</span>

  3. <span>$ 30cm $</span>

  4. <span>$ 40cm $</span>
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$B _{axial} = \displaystyle \frac{\mu _0}{4\pi} \frac{2Mr}{(r^2-l^2)^2}$
$B _{20} : B _{30} = 128  :  27$
$\displaystyle \frac{20}{(20^2 - l^2)^2} \times \frac{(30^2 - l^2)^2}{30} = \frac{128}{127}$
$2 (30^2 - l^2)^2 (27) = 3 (20^2 - l^2)^2 128$
$\sqrt{54}(900 - l^2) = \sqrt{384} (400 - l^2)$
$900 \sqrt{54} - \sqrt{54}l^2 = \sqrt{384} \times 400 - \sqrt{384}l^2$
$l^2 (12.2474) = 12224. 75$
$l^2 = 100 ;  l = \sqrt{100}-10 cm$
$\therefore$ Magnetic length $=2l = 20 cm$

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

A magnetic induction due to a short bar magnet of magnetic moment 5.4 A m$^2$ at a distance of 30 cm on the equatorial line is :

  1. $2 \times 10^{-4}T$

  2. $2 \times 10^{-5}T$

  3. $3 \times 10^{-5}T$

  4. $3 \times 10^{-4}T$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

$B _{equi} = \displaystyle \frac{\mu _0}{4 \pi } \frac{\mu}{r^3} = \frac{10^{-7}\times 5.4}{(0.3)^3} = 2 \times 10^{-5}T$

Multiple choice physics magnetism the bar magnet magnetic field due to bar magnet intensity of magnetic field and torque on a bar magnet

The magnetic induction due to short bar magnet on its axial line at a distance 'd' is 'B'. What is the magnetic induction due to the same bar magnet on the same line at a distance $\displaystyle \frac{4d}{5}?$

  1. <span>$\displaystyle \frac{125}{4}B$</span>

  2. <span>$\displaystyle \frac{125}{32}B$</span>

  3. <span>$\displaystyle \frac{125}{64}B$</span>

  4. <span>$\displaystyle \frac{125}{16}B$</span>
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$B = \displaystyle \frac{\mu _0  2M}{4 \pi  d^3}$
At $(4d/5) $ distance
$B' = \displaystyle \frac{\mu _0  2M}{4 \pi \left ( \frac{4d}{5} \right )^3} = \frac{\mu _0  2M}{4  \pi (d^3)} \left ( \frac{125}{64} \right )$
$=\displaystyle \frac{125}{64}B$