Video Lecture
Theory For Making Notes
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Practice Questions (Level-1)
1.
Magnets cannot be made from which of the following substances
(a) Iron
(b) Nickel
(c) Copper
(d) All of the above
Ans (c)
2.
The magnetic moment of atomic neon is
(a) Zero
(b) \mu B/2
(c) \mu B
(d) 3\mu B/2
Ans (a)
3.
Which of the following is most suitable for the core of electromagnets (a) Soft iron
(b) Steel
(c) Copper-nickel alloy
(d) Air
Ans (a)
4.
Substances in which the magnetic moment of a single atom is not zero, is known as
(a) Diamagnetism
(b) Ferromagnetism
(c) Paramagnetism
(d) Ferrimagnetism
Ans (c)
5.
If a diamagnetic solution is poured into a U-tube and one arm of this U-tube placed between the poles of a strong magnet with the meniscus in a line with the field, then the level of the solution will
(a) Rise
(b) Fall
(c) Oscillate slowly
(d) Remain as such
Ans (b)
6.
The magnetic susceptibility does not depend upon the temperature in
(a) Ferrite substances
(b) Ferromagnetic substances
(c) Diamagnetic substances
(d) Paramagnetic substances
Ans (c)
7.
The magnetic susceptibility is negative for
(a) Paramagnetic materials
(b) Diamagnetic materials
(c) Ferromagnetic materials
(d) Paramagnetic and ferromagnetic materials
Ans (b)
8.
Curie temperature is the temperature above which
(a) A paramagnetic material becomes ferromagnetic
(b) A ferromagnetic material becomes paramagnetic
(c) A paramagnetic material becomes diamagnetic
(d) A ferromagnetic material becomes diamagnetic
Ans (b)
9.
A frog can be deviated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as
(a) Paramagnetic
(b) Diamagnetic
(c) Ferromagnetic
(d) Antiferromagnetic
Ans (b)
10.
Which one of the following is a non-magnetic substance
(a) Iron
(b) Nickel
(c) Cobalt
(d) Brass
Ans (d)
11.
Liquid oxygen remains suspended between two pole faces of a magnet because it is
(a) Diamagnetic
(b) Paramagnetic
(c) Ferromagnetic
(d) Antiferromagnetic
Ans (b)
12.
For an isotropic medium B, m, H and M are related as (where B,\,\,{{\mu }_{0}},\,\,H and M have their usual meaning in the context of magnetic material
(a) (B-M)={{\mu }_{0}}H
(b) M={{\mu }_{0}}(H+M)
(c) H={{\mu }_{0}}(H+M)
(d) B={{\mu }_{o}}(H+M)
Ans (d)
Practice Questions (Level-2)
Q.1
The magnetic H-field at the center of a circular conductor is of radius ‘a’ and number of turns ‘N’ carrying current I is
(a) H=\frac{{NI}}{{2a}}
(b) H=\frac{{{{\mu }_{0}}NI}}{{2a}}
(c) H=\frac{{NI}}{a}
(d) H=\frac{{NI}}{{2\pi a}}
Ans : (a)
Q.2
The magnetic H-field due to a long, straight conductor carrying current I at a distance d is
(a) \frac{{{{\mu }_{0}}}}{{4\pi }}\frac{I}{d}
(b) \frac{{{{\mu }_{0}}}}{{2\pi }}\frac{I}{d}
(c) \frac{I}{{2\pi d}}
(d) \frac{I}{{2\pi {{d}^{2}}}}
Ans : (c)
3.
The material of permanent magnet has
(a) High retentivity, low coercivity
(b) Low retentivity, high coercivity
(c) Low retentivity, low coercivity
(d) High retentivity, high coercivity
Ans (d)
4.
The magnetic susceptibility is
(a) \chi =\frac{I}{H}
(b) \chi =\frac{B}{H}
(c) \chi =\frac{M}{V}
(d) \chi =\frac{M}{H}
Ans (a)
5.
The relative permeability is represented by mr and the susceptibility is denoted by c for a magnetic substance. Then for a paramagnetic substance
(a) μ< 1, χ< 0
(b) μ< 1, χ> 0
(c) μ> 1, χ< 0
(d) μ> 1, χ> 0
Ans (d)
6.
Relative permeability of iron is 5500, then its magnetic susceptibility will be
(a) 5500 x 107
(b) 5500 x 10–7
(c) 5501
(d) 5499
Ans (d)
7.
If the angular momentum of an electron is \overrightarrow{{J\,}} then the magnitude of the magnetic moment will be
(a) \frac{{eJ}}{{2m}}
(b) \frac{{eJ}}{{m}}
(c) eJ 2m
(d) \frac{{2m}}{{eJ}}
Ans (a)
8.
Which of the following statements is incorrect about hysteresis
(a) This effect is common to all ferromagnetic substances
(b) The hysteresis loop area is proportional to the thermal energy developed per unit volume of the material
(c) The hysteresis loop area is independent of the thermal energy developed per unit volume of the material
(d) The shape of the hysteresis loop is characteristic of the material
Ans (a)
9.
Curies law can be written as
(a) \chi \propto (T-{{T}_{c}})
(b) \chi \propto \frac{1}{{T-{{T}_{c}}}}
(c) \chi \propto \frac{1}{T}
(d) \chi \propto T
Ans (c)
10.
If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material denoted by {{\mu }_{d}},\,{{\mu }_{p}},\,{{\mu }_{f}}respectively then
(a) {{\mu }_{d}}\ne \text{ 0 and }{{\mu }_{f}}\ne \text{ 0}
(b) {{\mu }_{p}}=\text{ 0 and }{{\mu }_{f}}\ne \text{ 0}
(c) {{\mu }_{d}}=\text{ 0 and }{{\mu }_{p}}\ne \text{ 0}
(d) {{\mu }_{d}}\ne \text{ 0 and }{{\mu }_{p}}=\text{ 0}
Ans (c)
11.
When a ferromagnetic material is heated to temperature above its Curie temperature, the material
(a) Is permanently magnetized
(b) Remains ferromagnetic
(c) Behaves like a diamagnetic material
(d) Behaves like a paramagnetic material
Ans (d)