This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “Classification of Magnetic Materials – 1”.
1. What will happen with magnetic materials is kept in an external magnetic field?
a) They will move
b) They will develop magnetic lines of force
c) They will create a permanent magnetic moment
d) They will be unaffected
View Answer
Explanation: Magnetic materials are the materials which can behave like magnets. When these materials are kept in an external magnetic field, they will create a permanent magnetic moment in it.
2. Magnetism originates due to rotational motion of charged particles.
a) True
b) False
View Answer
Explanation: Magnetism originates from a magnetic moment of the magnetic materials due to the rotational motion of the charged particles. When an electron revolves around the positive nucleus, orbital magnetic moment arises.
3. What is the name of the continuous curve in the magnetic field, the tangent of which gives the direction of magnetic intensity?
a) Magnetic lines of force
b) Magnetic lines of induction
c) Magnetic force
d) Magnetic dipole moment
View Answer
Explanation: Magnetic lines of force are defined as the continuous curve in a magnetic field. The tangent drawn at any point on the curve gives the direction of the resultant magnetic field at that point.
4. What is the name of the magnetic lines which forms a closed path?
a) Magnetic lines of force
b) Magnetic force between two poles
c) Magnetic field
d) Magnetic lines of induction
View Answer
Explanation: The magnetic lines of force which originate from North Pole to South Pole doesn’t end there itself. They are supposed to continue through the magnet and reach the North Pole from where they started and forms a closed loop. Such lines are called magnetic lines of induction.
5. How is the residual magnetism from material removed?
a) Retentivity
b) Coercivity
c) Magneton
d) Switching off the magnetic field
View Answer
Explanation: The residual magnetism can be completely removed from the material by applying a reverse magnetic field. Hence coercivity of magnetic material is the strength of the reverse magnetic field which is used to completely demagnetise the material.
6. In which of the following magnetic moment is zero?
a) Dia-magnetic material
b) Parra-magnetic material
c) Ferromagnetic material
d) Ferrimagnetic material
View Answer
Explanation: In a diamagnetic material, the electron orbits are more or less random, and mostly all the magnetic moments are cancelled. Similarly, all the spins are almost paired. Hence the net magnetic moment in the diamagnetic material is zero.
7. Which of the following is a weak magnet?
a) Ferromagnetic material
b) Antiferromagnetic
c) Paramagnetic
d) Diamagnetic
View Answer
Explanation: The diamagnets are called weak magnets because there is no permanent dipole moment. Their net magnetic moment is zero.
8. When does a diamagnetic material become normal material?
a) At critical temperature
b) Above critical temperature
c) Never
d) Below critical temperature
View Answer
Explanation: Critical temperature is the temperature at which properties like magnetism changes. When the temperature is less than the critical temperature, diamagnetic material becomes a normal magnet.
9. Magnetic susceptibility is negative for paramagnetic material.
a) True
b) False
View Answer
Explanation: Magnetic susceptibility is positive for paramagnetic material. It is given by Curie-Weiss law, Susceptibility = C/(T-θ)
Where C = Curie constant
T = Absolute temperature
θ = Curie temperature.
10. When does a paramagnetic material become diamagnetic material?
a) At critical temperature
b) Above critical temperature
c) Below critical temperature
d) Never
View Answer
Explanation: Critical temperature is the temperature at which properties like magnetism changes. When the temperature is less than the critical temperature, the diamagnetic material becomes a normal magnet.
Sanfoundry Global Education & Learning Series – Engineering Physics.
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