501. Which of the following has the highest magnetic permeability?
A) Air
B) Steel
C) Soft iron
D) Copper
Ans: C
502. The resistivity of a semiconductor ___ with rise in temperature.
A) Increases
B) Decreases
C) Remains constant
D) Becomes infinite
Ans: B
503. The main constituent of glass is
A) Silica
B) Alumina
C) Lime
D) Soda
Ans: A
504. The magnetic property which determines the ease of magnetization is
A) Retentivity
B) Coercivity
C) Permeability
D) Hysteresis loss
Ans: C
505. The atomic structure of metals has
A) Tightly bound valence electrons
B) Loosely bound valence electrons
C) No valence electrons
D) Free protons
Ans: B
506. A dielectric material must have
A) High resistivity
B) High permeability
C) High conductivity
D) Low insulation resistance
Ans: A
507. The conduction in electrolytes is due to
A) Electrons
B) Ions
C) Holes
D) Atoms
Ans: B
508. The electric flux density is measured in
A) C/m
B) C/m²
C) V/m
D) Wb/m²
Ans: B
509. The energy stored in a magnetic field is proportional to
A) H²
B) B²
C) B×H
D) B/H
Ans: C
510. Which of the following is not a good magnetic material?
A) Nickel
B) Iron
C) Copper
D) Cobalt
Ans: C
511. The dielectric strength of vacuum is approximately
A) Infinite
B) 30 kV/cm
C) 10 kV/cm
D) 100 kV/cm
Ans: B
512. The conductivity of intrinsic semiconductors increases with
A) Decrease in temperature
B) Increase in temperature
C) Constant temperature
D) Pressure
Ans: B
513. Magnetic susceptibility χ is related to permeability μ by
A) μ = μ₀(1 + χ)
B) μ = μ₀(1 − χ)
C) μ = μ₀χ
D) μ = μ₀/χ
Ans: A
514. Which of the following is used for making thermistors?
A) Ferrite materials
B) Carbon
C) Silicon
D) Nickel
Ans: A
515. Electrical contact materials should have
A) High hardness
B) High conductivity
C) Low resistivity
D) All of these
Ans: D
516. In a dielectric, when the applied field is removed, polarization disappears. Such a material is
A) Ferroelectric
B) Paraelectric
C) Piezoelectric
D) Electrostrictive
Ans: B
517. The main purpose of annealing in metals is
A) To harden
B) To soften and relieve stresses
C) To increase resistivity
D) To make brittle
Ans: B
518. Which of the following is a good conductor but poor mechanical strength?
A) Silver
B) Aluminum
C) Copper
D) Graphite
Ans: A
519. The resistance of an intrinsic semiconductor at absolute zero is
A) Zero
B) Infinite
C) Finite
D) None
Ans: B
520. The property of a material to return to its original magnetic condition after magnetization is called
A) Retentivity
B) Coercivity
C) Permeability
D) Elasticity
Ans: B
521. The hysteresis loop area represents
A) Magnetic flux
B) Energy loss per cycle per unit volume
C) Magnetic permeability
D) Inductance
Ans: B
522. The main purpose of alloying copper is to
A) Increase conductivity
B) Improve mechanical properties
C) Reduce cost
D) Reduce oxidation
Ans: B
523. Which of the following is a good insulator at room temperature?
A) Mica
B) Silicon
C) Germanium
D) Graphite
Ans: A
524. The resistivity of nichrome is about
A) 1.1×10⁻⁶ Ωm
B) 1.1×10⁻⁴ Ωm
C) 10⁻⁸ Ωm
D) 10⁻³ Ωm
Ans: B
525. The magnetic field strength H is measured in
A) Tesla
B) Weber
C) Ampere-turns/m
D) Gauss
Ans: C
526. The loss of magnetism in a magnetic material when heated is called
A) Retentivity
B) Curie effect
C) Coercivity
D) Demagnetization
Ans: B
527. A good insulating oil should have
A) High dielectric strength
B) High flash point
C) Low viscosity
D) All of these
Ans: D
528. The energy gap in insulators is
A) 0 eV
B) 1 eV
C) >5 eV
D) <1 eV
Ans: C
529. Hard magnetic materials are used for
A) Transformer cores
B) Electromagnets
C) Permanent magnets
D) Relays
Ans: C
530. The temperature coefficient of resistance for metals is
A) Positive
B) Negative
C) Zero
D) Variable
Ans: A
531. Magnetic materials lose magnetism when
A) Heated above Curie temperature
B) Cooled below Curie temperature
C) Exposed to light
D) Electrified
Ans: A
532. Anisotropic materials have properties that
A) Are same in all directions
B) Vary with direction
C) Are zero
D) Are negative
Ans: B
533. The property of a material to get magnetized easily is called
A) Permeability
B) Retentivity
C) Coercivity
D) Magnetostriction
Ans: A
534. The resistivity of aluminum is about
A) 2.7×10⁻⁸ Ωm
B) 1.7×10⁻⁸ Ωm
C) 4.5×10⁻⁸ Ωm
D) 6×10⁻⁸ Ωm
Ans: A
535. The dielectric constant of mica is approximately
A) 1
B) 3–6
C) 10–20
D) 50–100
Ans: B
536. The permeability of free space μ₀ equals
A) 4π×10⁻⁷ H/m
B) 8.85×10⁻¹² H/m
C) 10⁻³ H/m
D) None
Ans: A
537. The property of some materials to change dimensions under electric field is
A) Piezoelectric effect
B) Magnetostriction
C) Hysteresis
D) Permittivity
Ans: A
538. A dielectric material is characterized by
A) Conductivity
B) Permittivity
C) Permeability
D) Resistivity only
Ans: B
539. The conductivity of an n-type semiconductor is mainly due to
A) Holes
B) Electrons
C) Both
D) Impurities only
Ans: B
540. The magnetization M is given by
A) B/H
B) (B − μ₀H)/μ₀
C) μH
D) B×H
Ans: B
541. Magnetic materials having narrow hysteresis loop are
A) Hard
B) Soft
C) Brittle
D) None
Ans: B
542. Which one is a soft magnetic material?
A) Steel
B) Silicon steel
C) Cobalt
D) Nickel
Ans: B
543. The relaxation time of electron in a conductor is of order
A) 10⁻⁹ s
B) 10⁻¹⁴ s
C) 10⁻³ s
D) 1 s
Ans: B
544. The Curie temperature of iron is about
A) 770°C
B) 1070°C
C) 570°C
D) 870°C
Ans: A
545. A capacitor stores energy in the form of
A) Electric field
B) Magnetic field
C) Mechanical stress
D) Thermal energy
Ans: A
546. Magnetostriction is a property exhibited by
A) Magnetic materials
B) Conductors
C) Insulators
D) Semiconductors
Ans: A
547. Carbon resistors are available up to about
A) 1 MΩ
B) 10 MΩ
C) 100 MΩ
D) 1 GΩ
Ans: B
548. The resistivity of silver is nearly
A) 1.6×10⁻⁸ Ωm
B) 2.7×10⁻⁸ Ωm
C) 5×10⁻⁸ Ωm
D) 1×10⁻⁸ Ωm
Ans: A
549. For an ideal dielectric, power loss is
A) Zero
B) Maximum
C) Minimum
D) Constant
Ans: A
550. The conductivity σ and resistivity ρ are related by
A) σ = 1/ρ
B) σ = ρ
C) σ = ρ²
D) σ = √ρ
Ans: A
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