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Physics M.C.Q [1M]

Magnetism and Matter · Bihar Board (BSEB) STD 12 Science (BSEB - English Medium). 24 questions.

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M.C.Q [1M]

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24 questions · timed · auto-graded

MCQ 11 Mark
Which of the following shows hysteresis ?
  • A
    Paramagnetic materials
  • ✓
    Ferromagnetic materials
  • C
    Diamagnetic materials
  • D
    None of these
Answer
Correct option: B.
Ferromagnetic materials
B
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MCQ 21 Mark
The value of magnetic potential at a distance $r$ from a pole strength $m$ is :
  • ✓
    $\frac{\mu_0 m}{4 \pi r}$
  • B
    $\frac{\mu_0 m}{4 \pi r^2}$
  • C
    $\frac{\mu_0 m}{4 \pi r^3}$
  • D
    zero
Answer
Correct option: A.
$\frac{\mu_0 m}{4 \pi r}$
A
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MCQ 31 Mark
On dividing any magnet of magnetic moment (M) parallel to its length into n equal pieces, the moment of each piece will be :
  • ✓
    $\frac{ M }{n}$
  • B
    $\frac{ M }{n^2}$
  • C
    $\frac{ M }{2 n}$
  • D
    $M \times n$
Answer
Correct option: A.
$\frac{ M }{n}$
A
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MCQ 41 Mark
The angle between magnetic meridian and geographical meridian is called :
  • A
    angle of dip
  • ✓
    angle of declination
  • C
    horizontal component of magnetic field
  • D
    criticle angle
Answer
Correct option: B.
angle of declination
B
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MCQ 51 Mark
The relation between geometrical length $(L_{g})$ of a magnet and its magnetic length $(L_{m})$ is :
  • ✓
    $L _{ m }=\frac{5}{6} L_g$
  • B
    $L _{ m }=\frac{6}{5} L_{ g }$
  • C
    $L_m=L_g$
  • D
    $L _{ m }=2 L_{ g }$

Answer
Correct option: A.
$L _{ m }=\frac{5}{6} L_g$
A
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MCQ 61 Mark
On going from north pole to equator, the value of angle of dip :
  • A
    Remains constant
  • B
    Increase
  • ✓
    Decreases
  • D
    First decreases and then increases
Answer
Correct option: C.
Decreases
C
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MCQ 81 Mark
If $\delta$ is the angle of dip at a place, then expression for $\tan \delta$ is :
  • ✓
    $B _{ V } / B _{ H }$
  • B
    $B _{ H } / B _{ V }$
  • C
    $B _{ V } B _{ H }$
  • D
    $\left(\frac{B_V}{B_H}\right)^2$
Answer
Correct option: A.
$B _{ V } / B _{ H }$
A
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MCQ 91 Mark
In earth's magnetic field $B_{H}$, if the frequency of oscillation of a magnetic needle is $n$, then :
  • A
    $n \propto B_{ H }$
  • ✓
    $n^2 \propto B_{ H }$
  • C
    $n \propto B _{ H ^2}$
  • D
    $n^2 \propto \frac{1}{B_H}$
Answer
Correct option: B.
$n^2 \propto B_{ H }$
B
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MCQ 101 Mark
The value of angle of dip at the earth's magnetic pole is :
  • A
    $0^{\circ}$
  • B
    $45^{\circ}$
  • ✓
    $90^{\circ}$
  • D
    $180^{\circ}$
Answer
Correct option: C.
$90^{\circ}$
C
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MCQ 111 Mark
The susceptibility of paramagnetic substance is :
  • ✓
    Constant
  • B
    Zero
  • C
    Infinity
  • D
    Depends on magnetic field
Answer
Correct option: A.
Constant
A
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MCQ 121 Mark
Magnetic dipole moment is a vector quantity directed from :
  • ✓
    South to North pole
  • B
    North to South pole
  • C
    East to West direction
  • D
    West to East direction
Answer
Correct option: A.
South to North pole
A
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MCQ 131 Mark
The dimensional formula of $\frac{1}{2}\in_{0}E^{2}$ is identical to :
  • ✓
    $\frac{B^2}{2 \mu_0}$
  • B
    $\frac{1}{2} B^2 \mu_0$
  • C
    $\frac{\mu_2^0}{2 B}$
  • D
    $\frac{1}{2} B \mu_2^0$
Answer
Correct option: A.
$\frac{B^2}{2 \mu_0}$
A
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MCQ 141 Mark
A circular coil of radius R carries a current I. The magnetic field at its center is B. At what distance from the center, on the axis of the coil, the magnetic field will be B/8 :
  • A
    $\sqrt{2} R$
  • B
    2R
  • ✓
    $\sqrt{3} R$
  • D
    3R
Answer
Correct option: C.
$\sqrt{3} R$
C
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MCQ 151 Mark
The magnetic moment of a steel rod of length 'l' is M. It is bent into a semi-circle. The new magnetic moment is :
Answer
Correct option: D.
$2 M / \pi$
(D) $2 M / \pi$
[Hints : $M = m \times l$. (Where $m =$ pole strength of the magnet)
When the rod of length $l$ is bent into a semi-circle then :
$I =\frac{\pi \times \text { Diameter }}{2} \Rightarrow$ Diameter $2l / \pi$, it is now the distance between the poles of semi-circular magnet. Hence the new magnetic moment
$\left.M ^{\prime}=m \times D =m \times 2 l / \pi=2 m l / \pi=2 M / \pi\right]$
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MCQ 171 Mark
When an ammeter is shunted its measuring range :
  • ✓
    Increases
  • B
    Decreases
  • C
    Remains constant
  • D
    None of these
Answer
Correct option: A.
Increases
A
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MCQ 181 Mark
When the intensity of magnetic field is increased four times the time period of suspended magnetic needle becomes :
  • A
    Double
  • ✓
    Half
  • C
    Four terms
  • D
    One-fourth less
Answer
Correct option: B.
Half
(B) Half
$[$ Hint $: T=2 \pi \sqrt{I / M B} \Rightarrow T \propto 1 / \sqrt{B}$
Where $I =$ Moment of inertia of suspended magnetic needle about axis of suspension and M = Magnetic moment of the needle. Hence when B is made four times T will become half.]
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MCQ 201 Mark
The permeability $\mu$ of a ferromagnetic substance is :
  • ✓
    $\mu \gg 1$
  • B
    $\mu=1$
  • C
    $\mu<1$
  • D
    $\mu=0$
Answer
Correct option: A.
$\mu \gg 1$
A
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MCQ 221 Mark
The magnetic field at the centre of a current carrying loop is B and its area is A. Magnetic moment of the loop will be :
  • A
    $BA ^2 / \mu_0 \pi$
  • B
    $BA ^{3 / 2} / \mu_0$
  • C
    $BA ^{3 / 2} / \mu_0 \pi$
  • ✓
    $2 BA ^{3 / 2} / \mu_0 \sqrt{\pi}$
Answer
Correct option: D.
$2 BA ^{3 / 2} / \mu_0 \sqrt{\pi}$
(D) $2 BA ^{3 / 2} / \mu_0 \sqrt{\pi}$
[Hint : Magnetic field at the centre of current carrying loop
$B =\frac{\mu_0 I }{2 a} ;$ where $a=$ radius of the loop
$\Rightarrow \quad I =2 aB / \mu_0$
$\therefore \quad M = I \times A$
$=\left(\frac{2 a B}{\mu_0}\right) \times A$
Now $\quad A =\pi a ^2 \Rightarrow a =( A / \pi)^{1 / 2}$
$M =\frac{2(A / \pi)^{1 / 2} B \times A }{\mu_0}$
$=\frac{2 A^{3 / 2} \cdot B}{\mu_0 \sqrt{\pi}}$
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MCQ 231 Mark
If the relative permeability of a substance is 0.999 then its nature is :
  • A
    paramagnetic
  • ✓
    diamagnetic
  • C
    ferromagnetic
  • D
    non-magnetic
Answer
Correct option: B.
diamagnetic
B
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MCQ 241 Mark
At any place on the earth vertical component of earth's magnetic field is $\sqrt{3}$ times of the horizontal component. Angle of dip at this place will be :
  • A
    $0^{\circ}$
  • B
    $30^{\circ}$
  • C
    $45^{\circ}$
  • ✓
    $60^{\circ}$
Answer
Correct option: D.
$60^{\circ}$
D
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