Engineering Physics Multiple Choice Questions on “Parameters”.
1. If a material is paramagnetic, what shall be the value of χ?
a) Negative
b) Small and positive
c) Large and Positive
d) Depends on other factors
Answer: b
Clarification: When a material is paramagnetic, the magnetic susceptibility, χ, is small and positive. For a diamagnetic material it is negative and for a ferromagnetic material, it is large and positive.
2. The vertical plane containing the earth’s axis of rotation is called as _____________
a) Geographic meridian
b) Magnetic Meridian
c) Magnetic Declination
d) Prime Meridian
Answer: a
Clarification: The vertical plane containing the longitude circle and the axis of rotation of the earth is called the geographic meridian. The plane passing through north pole and south pole is called magnetic meridian.
3. Where would the declination be greater?
a) India
b) Africa
c) Egypt
d) Arctic
Answer: d
Clarification: The magnetic declination is greater at higher latitudes and smaller near the equator. Thus, it would be greater in the Arctic region and smaller near equator.
4. In case of diamagnetic materials, M and H are opposite in direction.
a) True
b) False
Answer: a
Clarification: It is due to the fact that M and H are opposite in direction in a diamagnetic material that the magnetic susceptibility for diamagnetic materials is small and negative.
5. How is the magnetic field, B, related to Magnetization, M?
a) B ∝ M
b) B ∝ 1/M
c) B ∝ M2
d) B ∝ 1/M2
Answer: a
Clarification: The Magnetic Field, B, is directly proportional to the Magnetization, M, of the material. The true expression is: B = μ0M.
6. The dimensions of χ are ____________
a) [AL]
b) [AL2T-1]
c) [AM2L4T]
d) Dimensionless
Answer: d
Clarification: χ is a dimensionless quantity and is called the magnetic susceptibility. It is used to identify the magnetic property of the material.
7. For a paramagnetic material, χ does not depend on Temperature.
a) True
b) False
Answer: b
Clarification: For a paramagnetic material, both the magnetic susceptibility and the permeability depend not only on the material but also on the sample temperature.
8. A solenoid carry a current of 2A. If the number of turns is 1000 per meter, what is the Magnetic Intensity?
a) 1000 A/m
b) 2000 A/m
c) 3000 A/m
d) 4000 A/m
Answer: b
Clarification: The field H is dependent on the material of the core and is
H = nI
= 1000 X 2
= 2000 A/m.
9. A solenoid has a core of a material with relative permeability 400. The windings are insulated from the core and the magnetic Intensity is 1500 A/m. What is the Magnetization of the core?
a) 0.25 T
b) 0.50 T
c) 0.75 T
d) 1.00 T
Answer: c
Clarification: The Magnetic field, B, is given by
B = μr μ0 H
= 400 X 4π X 10-7 X 1500
= 0.75 T.
10. Which material is shown in the figure?
a) Diamagnetic Material
b) Paramagnetic Material
c) Ferromagnetic Material
d) Non-Magnetic Material
Answer: a
Clarification: The material shown in the figure is diamagnetic material. Diamagnetic materials are those which have tendency to move forward stronger to the weaker part of the external magnetic field.
11. If for a material, the magnetization is 8 X 105 A/m and the relative permeability is 200, what is the Magnetic Intensity?
a) 4.89 X 103 A/m
b) 4.64 X 103 A/m
c) 4.43 X 103 A/m
d) 4.02 X 103 A/m
Answer: d
Clarification: Magnetization is given by: M = (μr – 1) H
8 X 105 = 199 X H
H = 4.02 X 103 A/m.
12. The earth’s magnetic field at the equator is approximately 0.4 G. What is the earth’s dipole moment?
a) 0.8 X 1023 Am2
b) 1.0 X 1023 Am2
c) 1.2 X 1023 Am2
d) 1.5 X 1023 Am2
Answer: b
Clarification: We know, BE = (frac{mu_0 m}{4pi r^3})
Given that, BE = 0.4 G = 4 X 10-5 T. For r, we take the radius of the earth 6.4 X 106 m.
Hence, m = 4 X 10-5 X (6.4 X 106)3 X 4π/μo
= 1.0 X 1023 Am2.
13. If the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26 G and the dip angle is 60°, what is the magnetic field of earth at this location?
a) 0.52 G
b) 0.46 G
c) 0.78 G
d) 0.94 G
Answer: a
Clarification: It is given that, HE = 0.26 G. Thus, we have
cos60° = HE/BE
BE = HE/ cos60°
= 0.26 X 2
= 0.52 G.
14. If the relative permeability of material lies between zero and one, the material is ____________
a) Diamagnetic Material
b) Paramagnetic Material
c) Ferromagnetic Material
d) Insufficient Information
Answer: a
Clarification: The given material is diamagnetic material. For a diamagnetic material, it’s magnetic susceptibility is small and negative while it’s relative permeability is small and positive as μr = 1 + χ.
15. Core of electromagnets are made up of ____________
a) Diamagnetic Material
b) Paramagnetic Material
c) Ferromagnetic Material
d) Plastic
Answer: c
Clarification: Ferromagnetic materials have high permeability and low retentivity. Due to these properties, the core of electromagnets is made up of ferromagnetic materials.