Advertisements
Advertisements
प्रश्न
A long solenoid has 1000 turns per metre and carries a current of 1 A. It has a soft iron core of µr = 1000. The core is heated beyond the Curie temperature, Tc.
- The H field in the solenoid is (nearly) unchanged but the B field decreases drastically.
- The H and B fields in the solenoid are nearly unchanged.
- The magnetisation in the core reverses direction.
- The magnetisation in the core diminishes by a factor of about 108.
विकल्प
a and d
c and d
b and d
b and c
Advertisements
उत्तर
a and d
Explanation:
The magnetic field intensity H = nl, where n = number of turns per metre of a solenoid and I = current and B = μ0μrI.
Also, at normal temperature, a solenoid behaves as a ferromagnetic substance and at the temperature beyond the Curie temperature, it behaves as a paramagnetic substance.
n = 1000 turns per metre, μr = 1000
H = nl = 1000 × 1 = 1000 Amp. So H is constant verifies the answer a
B = μ0μr nl = (μ0nl)μr = Kμr (K = constant)
So, `B oo μ_r`
but there is a large decrease in the susceptibility of the core on heating it beyond critical temperature, hence magnetic field will decrease drastically. Now, for magnetisation in the core, when temperature of the iron core of a solenoid is raised beyond Curie temperature, then it behaves as a paramagnetic material, where
and `(chi_m)_(Fero) ≈ 10^3`
`(chi_m)_(Para) ≈ 10^-5`
⇒ `((chi_m)_(Fero))/((chi_m)_(Para)) = 10^3/10^-5 = 10^8`
APPEARS IN
संबंधित प्रश्न
In what way is the behaviour of a diamagnetic material different from that of a paramagnetic, when kept in an external magnetic field?
Out of the two magnetic materials, 'A' has relative permeability slightly greater than unity while 'B' has less than unity. Identify the nature of the materials 'A' and 'B'. Will their susceptibilities be positive or negative?
The susceptibility of a magnetic material is 0·9853. Identify the type of magnetic material. Draw the modification of the field pattern on keeping a piece of this material in a uniform magnetic field.
Identify the following magnetic materials :
There are three needles 'N1', 'N2' and 'N3' made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. When a magnet is brought close to them, then it will ____________.
Above the curie temperature the susceptibility of ferromagnetic substance varies ____________.
A short bar magnet has a magnetic moment of 0.48 J T−1. Give the direction and magnitude of the magnetic field produced by the magnet at a distance of 10 cm from the centre of the magnet on
- the axis,
- the equatorial lines (normal bisector) of the magnet.
Which graph shows the variation of magnetic susceptibility (`chi`) with magnetizing field (H) for a paramagnetic substance?
If a toroid uses bismuth for its core, will the field in the core be (slightly) greater or (slightly) less than when the core is empty?
The coercivity of a small magnet where the ferromagnet gets demagnetized is 3 × 103 Am–1. The current required to be passed in a solenoid of length 10 cm and number of turns 100, so that the magnet gets demagnetized when inside the solenoid, is ______.
The magnetic susceptibility for diamagnetic materials is ______.
A hydrogen atom is paramagnetic. A hydrogen molecule is
If a charged particle at rest experience no electromagnetic force
According to the Atomic theory, on heating a magnet, the thermal energy of the elementary magnet ______
A paramagnetic sample shows a net magnetisation of 8 Am–1 when placed in an external magnetic field of 0.6 T at a temperature of 4 K. When the same sample is placed in an external magnetic field of 0.2 T at a temperature of 16 K, the magnetisation will be ______.
A uniform magnetic field gets modified as shown in figure when two specimens A and B are placed in it.
 |
 |
| (a) | (b) |
- Identify the specimen A and B.
- How is the magnetic susceptibility of specimen A different from that of specimen B?
Explain ferromagnetism on the basis of the domain theory.
Explain the Domain theory in brief.
Magnetic susceptibility of a diamagnetic substance ______.
