401. The energy band gap of silicon at room temperature is about
A) 1.1 eV
B) 0.7 eV
C) 1.43 eV
D) 3 eV
Ans: A
402. The energy band gap of germanium is
A) 0.72 eV
B) 1.1 eV
C) 1.43 eV
D) 2.2 eV
Ans: A
403. The energy band gap of GaAs is approximately
A) 1.43 eV
B) 0.7 eV
C) 2.5 eV
D) 3.4 eV
Ans: A
404. In p-type semiconductor, the majority carriers are
A) Holes
B) Electrons
C) Ions
D) Both
Ans: A
405. In n-type semiconductor, the minority carriers are
A) Holes
B) Electrons
C) Ions
D) None
Ans: A
406. The resistivity of intrinsic semiconductor decreases with
A) Increase in temperature
B) Decrease in temperature
C) Increase in voltage
D) None
Ans: A
407. The dopant used to create p-type silicon is
A) Boron
B) Phosphorus
C) Arsenic
D) Antimony
Ans: A
408. The dopant used to create n-type silicon is
A) Phosphorus
B) Boron
C) Aluminum
D) Gallium
Ans: A
409. The Hall voltage is proportional to
A) Magnetic field and current
B) Current only
C) Voltage
D) Temperature
Ans: A
410. The Hall coefficient is negative for
A) N-type semiconductor
B) P-type semiconductor
C) Insulator
D) Metal
Ans: A
411. Dielectric materials are characterized by
A) Permittivity
B) Permeability
C) Conductivity
D) Magnetic susceptibility
Ans: A
412. Polarization in dielectrics is
A) Electric dipole alignment
B) Magnetic alignment
C) Current flow
D) Heat conduction
Ans: A
413. The breakdown in a dielectric occurs when
A) Field exceeds dielectric strength
B) Current exceeds rated value
C) Temperature rises
D) None
Ans: A
414. Piezoelectric effect is used in
A) Crystal oscillators
B) Electric heaters
C) Transformers
D) Inductors
Ans: A
415. Quartz crystal exhibits
A) Piezoelectric effect
B) Photoelectric effect
C) Seebeck effect
D) Magnetostriction
Ans: A
416. The dielectric constant of mica is around
A) 6
B) 3
C) 1
D) 10
Ans: A
417. A good dielectric should have
A) High dielectric strength and low loss
B) High loss factor
C) High conductivity
D) None
Ans: A
418. In electrostriction, deformation depends on
A) Square of electric field
B) Linear electric field
C) Magnetic field
D) Frequency
Ans: A
419. Magnetic flux lines never
A) Intersect
B) Close
C) Rotate
D) End on poles
Ans: A
420. Magnetic reluctance depends on
A) Length and area of core
B) Permeability
C) Both A and B
D) None
Ans: C
421. The energy stored in a magnetic field is proportional to
A) Square of current
B) Magnetic field
C) Flux
D) Voltage
Ans: A
422. Ferroelectric materials are used in
A) Non-volatile memories
B) Heaters
C) Transformers
D) Motors
Ans: A
423. The B-H loop area represents
A) Hysteresis loss per cycle
B) Magnetic strength
C) Flux density
D) Saturation
Ans: A
424. The unit of magnetic flux density is
A) Tesla
B) Weber
C) Henry
D) Farad
Ans: A
425. Resistivity of aluminum is about
A) 2.7×10⁻⁸ Ω·m
B) 1.6×10⁻⁸ Ω·m
C) 10⁻⁶ Ω·m
D) 3.4×10⁻⁸ Ω·m
Ans: A
426. Resistivity of copper is approximately
A) 1.7×10⁻⁸ Ω·m
B) 3.0×10⁻⁸ Ω·m
C) 10⁻⁶ Ω·m
D) 2.7×10⁻⁸ Ω·m
Ans: A
427. The unit of magnetic reluctance is
A) A/Wb
B) Wb/A
C) H
D) H⁻¹
Ans: A
428. Magnetic saturation occurs when
A) Domains fully aligned
B) No field applied
C) Reverse field applied
D) None
Ans: A
429. The resistivity of nichrome is about
A) 1.1×10⁻⁶ Ω·m
B) 10⁻⁸ Ω·m
C) 10⁻⁴ Ω·m
D) 10⁻² Ω·m
Ans: A
430. A material with low hysteresis loss is desirable for
A) Transformers
B) Permanent magnets
C) Motors
D) Both A and C
Ans: D
431. Insulating material for high voltage cables is
A) XLPE
B) PVC
C) Rubber
D) Cotton
Ans: A
432. High resistivity alloys are used in
A) Resistors
B) Thermocouples
C) Heating coils
D) All
Ans: D
433. Magnetic shielding is done using
A) Soft iron
B) Copper
C) Aluminum
D) Brass
Ans: A
434. The function of varnish in windings is
A) Insulation and mechanical strength
B) Reduce resistance
C) Increase inductance
D) Cool winding
Ans: A
435. Ferrites are
A) Ceramic magnetic materials
B) Metallic conductors
C) Semiconductors
D) Non-magnetic
Ans: A
436. Magnetic materials are used in data storage due to
A) Hysteresis property
B) High resistivity
C) Conductivity
D) Heat tolerance
Ans: A
437. A paramagnetic material shows magnetization proportional to
A) Magnetic field
B) Square of field
C) Temperature
D) None
Ans: A
438. The resistivity of carbon is about
A) 3×10⁻⁵ Ω·m
B) 1×10⁻⁸ Ω·m
C) 10⁻⁶ Ω·m
D) 1 Ω·m
Ans: A
439. The dielectric constant of vacuum is
A) 1
B) 8.85×10⁻¹²
C) 0
D) 2
Ans: A
440. Copper is preferred over aluminum in cables because
A) Lower resistivity
B) Higher strength
C) More durable
D) All
Ans: D
441. Hard magnetic materials are used in
A) Loudspeakers
B) Relays
C) Transformers
D) Magnets
Ans: D
442. Transformer steel sheets are laminated to reduce
A) Eddy current loss
B) Hysteresis loss
C) Magnetic flux
D) Weight
Ans: A
443. In superconductors, critical temperature depends on
A) Material
B) Current
C) Pressure
D) All
Ans: A
444. In dielectric materials, energy is stored as
A) Electric field energy
B) Magnetic energy
C) Heat
D) None
Ans: A
445. Electrical steel has silicon content of
A) 3–4%
B) 0.1%
C) 10%
D) 15%
Ans: A
446. Magnetic susceptibility of diamagnetic material is
A) Small and negative
B) Small and positive
C) Large and positive
D) Zero
Ans: A
447. Permanent magnet materials include
A) Alnico
B) Ferrites
C) Cobalt steel
D) All
Ans: D
448. Soft magnetic materials have
A) Narrow hysteresis loop
B) High coercivity
C) High hysteresis
D) None
Ans: A
449. The electric dipole moment is measured in
A) Coulomb-metre
B) Ampere-turn
C) Weber
D) Volt
Ans: A
450. The resistivity of silicon increases when
A) Doping decreases
B) Temperature increases
C) Doping increases
D) None
Ans: A
451. The domain theory explains
A) Ferromagnetism
B) Paramagnetism
C) Diamagnetism
D) None
Ans: A
452. The unit of permeability is
A) H/m
B) Wb/m²
C) A/m
D) H
Ans: A
453. Curie temperature of iron is
A) 770°C
B) 358°C
C) 100°C
D) 200°C
Ans: A
454. The conductivity of copper at room temperature is about
A) 5.8×10⁷ S/m
B) 1×10⁶ S/m
C) 10⁴ S/m
D) 10⁸ S/m
Ans: A
455. The magnetization curve flattens when
A) Saturation occurs
B) Hysteresis reduces
C) Coercivity increases
D) Temperature decreases
Ans: A
456. Semiconductor diodes work due to
A) PN junction
B) Magnetic effect
C) Polarization
D) Resistance
Ans: A
457. Copper is a
A) Diamagnetic material
B) Paramagnetic
C) Ferromagnetic
D) None
Ans: A
458. The dielectric constant of glass is approximately
A) 5–10
B) 1
C) 50
D) 100
Ans: A
459. The temperature coefficient of resistance for metals is
A) Positive
B) Negative
C) Zero
D) Nonlinear
Ans: A
460. The temperature coefficient of resistance for semiconductors is
A) Negative
B) Positive
C) Zero
D) Constant
Ans: A
461. Resistance of an insulator is
A) Very high
B) Very low
C) Constant
D) None
Ans: A
462. Magnetizing force depends on
A) Number of turns and current
B) Core area
C) Magnetic flux
D) Field lines
Ans: A
463. Energy stored in magnetic field per unit volume =
A) ½ BH
B) ½ μH²
C) ½ LI²
D) All are same
Ans: D
464. The dielectric loss tangent is ratio of
A) Conductive to reactive current
B) Voltage to current
C) Field to flux
D) None
Ans: A
465. Conductivity (σ) is reciprocal of
A) Resistivity (ρ)
B) Permeability (μ)
C) Permittivity (ε)
D) Reluctivity
Ans: A
466. Non-crystalline solids are called
A) Amorphous
B) Crystalline
C) Polycrystalline
D) Isotropic
Ans: A
467. Magnetostriction materials are used in
A) Ultrasonic transducers
B) Transformers
C) Batteries
D) None
Ans: A
468. For minimum energy loss in transformer core, material should have
A) High resistivity and low hysteresis loss
B) High permeability and low retentivity
C) Both A and B
D) None
Ans: C
469. Common ferromagnetic materials include
A) Iron, cobalt, nickel
B) Copper, aluminum
C) Carbon, silicon
D) None
Ans: A
470. The thermal conductivity of metals is mainly due to
A) Free electrons
B) Phonons
C) Ions
D) Lattice
Ans: A
471. The process of removing magnetization is called
A) Demagnetization
B) Depolarization
C) Retardation
D) Neutralization
Ans: A
472. Magnetic materials are classified based on
A) Magnetic susceptibility
B) Permeability
C) Temperature
D) Resistivity
Ans: A
473. The resistivity of alloys is generally
A) Higher than pure metals
B) Lower
C) Same
D) Constant
Ans: A
474. Semiconductor devices work due to
A) Controlled conductivity
B) Magnetic effect
C) Thermal conductivity
D) Polarization
Ans: A
475. The hysteresis loss per cycle per unit volume is proportional to
A) Area of B-H loop
B) Square of H
C) Square of B
D) None
Ans: A
476. The product of permeability and permittivity gives
A) 1/(velocity of light)²
B) Speed of sound
C) Magnetic flux
D) None
Ans: A
477. Electrical strain gauges work on
A) Variation of resistance with strain
B) Magnetic property
C) Capacitance
D) None
Ans: A
478. The phenomenon of energy loss in magnetic materials is called
A) Hysteresis loss
B) Eddy loss
C) Retentivity
D) Coercivity
Ans: A
479. Dielectric strength is measured in
A) kV/mm
B) A/m
C) Ω·m
D) Wb/m²
Ans: A
480. Copper has high conductivity because of
A) Free electrons
B) Ions
C) Covalent bonding
D) None
Ans: A
481. Thermal resistivity is reciprocal of
A) Thermal conductivity
B) Electrical conductivity
C) Specific heat
D) Density
Ans: A
482. Electrical strain in dielectric =
A) E/ε
B) ε/E
C) σ/E
D) D/E
Ans: D
483. The Curie temperature is point where
A) Ferromagnetism ceases
B) Diamagnetism starts
C) Paramagnetism starts
D) Both A and C
Ans: D
484. Resistivity of semiconductor depends on
A) Temperature and impurities
B) Pressure
C) Voltage
D) All
Ans: A
485. Saturation magnetization decreases with
A) Increase in temperature
B) Decrease in temperature
C) Constant
D) None
Ans: A
486. Electron mobility is measured in
A) m²/V·s
B) m/s
C) V/m
D) A/m²
Ans: A
487. The dielectric constant of paper is around
A) 2–4
B) 10
C) 50
D) 100
Ans: A
488. Magnetic domains are
A) Regions of aligned dipoles
B) Random spins
C) Non-magnetic zones
D) Empty lattice points
Ans: A
489. Magnetic flux density (B) and field strength (H) relation:
A) B = μH
B) H = μB
C) B = H/μ
D) None
Ans: A
490. Eddy current loss can be reduced by
A) Laminating the core
B) Increasing flux
C) Using thicker sheets
D) Increasing frequency
Ans: A
491. Resistivity of metals increases due to
A) Impurities and temperature
B) Magnetic field
C) Electric field
D) Pressure
Ans: A
492. The electric displacement vector D =
A) εE
B) E/ε
C) ρE
D) E²/2
Ans: A
493. Copper and silver are best conductors because
A) Large number of free electrons
B) High mobility
C) Both A and B
D) None
Ans: C
494. A semiconductor with equal number of electrons and holes is
A) Intrinsic
B) Extrinsic
C) Degenerate
D) Compensated
Ans: A
495. The Fermi level lies near valence band in
A) P-type semiconductor
B) N-type
C) Intrinsic
D) Metal
Ans: A
496. The Fermi level lies near conduction band in
A) N-type semiconductor
B) P-type
C) Intrinsic
D) Insulator
Ans: A
497. The drift current in semiconductor depends on
A) Electric field
B) Mobility
C) Carrier concentration
D) All
Ans: D
498. The diffusion current flows due to
A) Concentration gradient
B) Electric field
C) Magnetic field
D) Temperature
Ans: A
499. Ferromagnetic materials exhibit
A) Spontaneous magnetization
B) Weak magnetization
C) No magnetization
D) None
Ans: A
500. The hysteresis loss in magnetic material is directly proportional to
A) Area of hysteresis loop
B) Frequency
C) Volume
D) All of these
Ans: D
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