Electrical Engineering Materials MCQ PDF Download

81. Ferroelectric materials are the dielectrics and analogous to………materials.

(a) diamagnetic
(b) paramagnetic
(c) ferromagnetic
(d) antiferromagnetic

SHOW ANSWER

82. Ferroelectrics are widely used as transducers.

(a) active
(b) passive
(c) electromechanical
(d) none of the above

SHOW ANSWER

83. The materials having permanent electric moment are known as

(a) electrets.
(b) dielectrics.
(c) semiconductors.
(d) none of the above.

SHOW ANSWER

84. Consider the following statements: Electrets are the materials which are

  1. having permanent electric moments.
  2. electromagnets.
  3. very similar to permanent magnet materials.
  4. similar to anti-ferroelectric materials.

Which of the above statements is/are correct?
(a) 2 only.
(b) 1 and 3 only.
(c) 2 and 3 only.
(d) 1, 2, 3 and 4.

SHOW ANSWER

85. Which one the following statements is correct?

(a) The absence of a hysteresis loop in a plot of polarization against field is proof of the absence of spontaneous polarization.
(b) The Curie temperature of a ferroelectric is the temperature above which its spontaneous polarization disappears.
(c) The Curie temperature of a ferroelectric is the temperature below which its spontaneous polarization disappears.
(d) Barium titanate is a ferroelectric because its lattice strains spontaneously above the Curie temperature.

SHOW ANSWER

86. Magnetic material in VHF applications is

(a) silicon steel.
(b) Alnico.
(c) cobalt salt.
(d) ferrite.

SHOW ANSWER

87. Air exhibits

(a) ferromagnetism.
(b) paramagnetism.
(c) anti-ferromagnetism.
(d) ferrimagnetism.

SHOW ANSWER

88. Soft magnetic material is

(a) tungsten steel.
(b) Alcomax.
(c) bismuth.
(d) iron.

SHOW ANSWER

89. Which one of the following materials can be used for permanent magnets?

(a) Alnico.
(b) Barium ferrite.
(c) Carbon steel.
(d) Iron-cobalt alloy.

SHOW ANSWER

90. Which one of the following is not a permanent magnetic material?

(a) Chromium steel.
(b) Silicon iron.
(c) Cobalt steel.
(d) Alnico.

SHOW ANSWER

91. Which among the following magnetic materials has the highest energy-product to make it a permanent magnet?

(a) Alnico.
(b) Ferrite.
(c) Samarium cobalt.
(d) Cobalt-iron alloy.

SHOW ANSWER

92. Which one of the following is correct? Ferrites are particularly suited for high frequency applications because of their

(a) low distortion.
(b) low eddy current loss.
(c) high conductivity.
(d) high mobility.

SHOW ANSWER

93. Up to about 4% silica is added in iron to be used as a soft magnetic material. The major reason for this is to

(a) increase permeability of the material.
(b) increase electrical resistivity of the material.
(c) increase the coercive force.
(d) increase the Saturation flux density.

SHOW ANSWER

94. Soft iron is used in the manufacture of electromagnets because of its

(a) high saturation magnetization only.
(b) low retentivity only.
(c) low coercive field only.
(d) high saturation magnetization, low retentivity and low coercive field.

SHOW ANSWER

95. Soft iron is used to manufacture electromagnets because it has

(a) high retentivity.
(b) high coercive field.
(c) low retentivity.
(d) low coercive field.

SHOW ANSWER

96. Magnetically hard materials do not possess which of the following characteristics?

(a) high retentivity.
(b) high coercivity.
(c) strong magnetic reluctance.
(d) zero differential permeability.

SHOW ANSWER

97. Which one of the following classes of materials can be categorized as ferities?

(a) Plastics.
(b) Metals.
(c) Alloys.
(d) Ceramics.

SHOW ANSWER

98. High frequency transformer cores are generally made of

(a) cast iron.
(b) mu-metal.
(c) ferrite.
(d) graphite.

SHOW ANSWER

99. A ferrite core has lower specific eddy current loss compared to an iron core because the ferrite core has

(a) higher electrical resistance.
(b) lower electrical resistance.
(c) higher permeability.
(d) lower permeability.

SHOW ANSWER

100. A coil wound on a magnetic core is excited from an ac source. The source voltage and its frequency are both doubled. What will be the eddy current loss in the core?

(a) Four times the original value.
(b) Double the original value.
(c) Same as the original value.
(d) Half the original value.

SHOW ANSWER

Leave a Comment

Your email address will not be published. Required fields are marked *