Magnetism and Matter- 2 Practice Questions - DPP for NEET

 Page 1


1. (a) Susceptibility of ferromagnetic substance is greater
than 1.
2. (c) Susceptibility of diamagnetic substance is negative and
it does not change with temperature.
3. (c) 0
d
m= and 
0
p
m¹
4. (d)
0
4
r
B
B
m==
5. (b) Dimagnetic
6. (b) Paramagnetic
7. (d) A super conductor exhibits perfect diamagnetism.
8. (a) Soft iron is highly ferromagnetic.
9. (a) Diamagnetism is the universal property of all
substances.
10. (c) Diamagnetic substances are repelled by magnetic field.
11. (b) Coercive force
12. (b) Because, diamagnetic substance, moves from stronger
magnetic field to weaker field.
13. (d) 1,0 m > c>
r
14. (b) Hysteresis curve for a given material estimates
hysteresis loss.
15. (a) Neon atom is diamagnetic, hence it’s net magnetic
moment is zero.
16. (b) On heating, different domains have net magnetisation
in them which are randomly distributes. Thus the net
magnetisation of the substance due to various domains
decreases to minimum.
17. (b) Repelled due to induction of similar poles.
18. (d) From the characteristic of
BH -
curve.
19. (c) Diamagnetic substances are feebly repelled by magnets.
20. (d) Net magnetic induction B = B
0
 + B
m
 = µ
0
H + µ
0
M
21. (d) ( 1) (5500 1) 5499
m rm
c=m - Þc= - =
22. (c) Q  m
r
 =
00
B
H
m
=
mm
or m
r
 = 
37
8
2 10 4 10
-
p
´ ´ p´
 = 10
4
23. (a)  W
H
 = V Aft = 
m
d
 Aft
or   W
H
 = 
3
0.6
7.8 10 ´
 × 0.722 × 50
              = 277.7 × 10
-5
  Joule
24. (c)
25. (b) Given that : H = 1600 Am
–1
 , f =2.4 ×10
–5
 Wb,
A = 0.2 cm
2
 = 0.2 × 10
–4
 m
2
.
B = magnetic flux per unit cross - sectional are
    = 
5
4
2.4 10
A
0.2 10
-
-
f´
=
´
 = 1.2 Wbm
–2
Magnetic permeability :
2
1
B 1.2 Wbm or T
H
1600 Am
-
-
m==
 = 7.5 × 10
–4
 T AA
–1
 m
As µ = µ
0
 (1 + x
m
)
\ x
m
 = 
4
7
0
µ 7.5 10
1
µ
4 3.14 10
-
-
´
-=
´´
           = 597.1 – 1 = 596.1.
26. (a) The energy lost per unit volume of a substance in a
complete cycle of magnetisation is equal to the area of
the hysteresis loop.
27. (a) Statement (4) is the only true statement among the given
choices.
28. (b) The susceptibility of ferromagnetic substance decreases
with the rise of temperature in a complicated manner.
After Curie's point the susceptibility of ferromagnetic
substance varies inversely with its absolute
temperature. Ferromagnetic substance obey’s Curies
law only above its Curie point.
29. (d) A paramagnetic sample display greater magnetisation
when cooled, this is because at lower temperature, the
tendency to disrupt the alignment of dipoles (due to
magnetising field) decreases on account of reduced
random thermal motion.
30. (d) The permeability of a ferromagnetic material dependent
on magnetic field, 
0
m
B=KB
u r ur
, where B
0
 is applied
field. The total magnetic field 
B
ur
 inside a ferromagnet
may be 10
3
 or 10
4
 times the applied field B
0
 The
permeability K
m
 of a ferromagnetic material is not
constant, neither the field B
ur
 nor the magnetization M
u ur
increases linearly with B
ur
 even at small value of B
0
.
From the hysteresis curve, magnetic permeability is
greater for lower field.