InterviewSolution

Explore topic-wise InterviewSolutions in .

This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.

51.	For a dielectric which of the following properties hold good?(a) They are superconductors at high temperatures(b) They are superconductors at low temperatures(c) They can never become a superconductor(d) They have very less dielectric breakdown voltageThis question was addressed to me in exam.My doubt is from Dielectrics in division Electric Fields in Material Space of Electromagnetic Theory
Answer»

52.	A dielectric can be made a conductor by(a) Compression(b) Heating(c) Doping(d) FreezingThis question was posed to me in an online interview.My question is taken from Dielectrics in division Electric Fields in Material Space of Electromagnetic Theory
Answer» Right option is (B) Heating Explanation: On increasing the TEMPERATURE, the free electrons in an insulator can be promoted from valence to CONDUCTION BAND. Gradually, it can act as a conductor through heating process. This condition is called DIELECTRIC breakdown, wherein the insulator loses its dielectric property and starts to conduct.

53.	The current flowing through an insulating medium is called(a) Conduction(b) Convection(c) Radiation(d) SusceptibilityI had been asked this question during an internship interview.My question is from Conductors topic in portion Electric Fields in Material Space of Electromagnetic Theory
Answer» Correct option is (B) Convection To elaborate: A beam of electrons in a vacuum tube is CALLED convection CURRENT. It occurs when current flows through an insulating medium LIKE liquid, vacuum etc.

54.	Identify a good dielectric.(a) Iron(b) Ceramics(c) Plastic(d) MagnesiumI got this question in an interview.My question is from Dielectrics in chapter Electric Fields in Material Space of Electromagnetic Theory
Answer» The CORRECT answer is (b) CERAMICS To explain I WOULD say: Iron and magnesium are metals. Hence they need not be considered. Both ceramics and plastic are INSULATORS. But dielectric constant is more for ceramics always. Hence ceramics is the BEST dielectric.

55.	A dielectric is always an insulator. But an insulator is not necessarily a dielectric. State True/False.(a) True(b) FalseThe question was posed to me during an online exam.My question comes from Dielectrics topic in section Electric Fields in Material Space of Electromagnetic Theory
Answer» Correct option is (a) True For explanation I would say: For a MATERIAL to be dielectric, its permittivity should be very high. This is seen in insulators. For a material to be INSULATOR, the CONDITION is to have large band gap energy. However, this is not necessary for a dielectric.

56.	Find the conduction current density when conductivity of a material is 500 units and corresponding electric field is 2 units.(a) 500(b) 250(c) 1000(d) 2000This question was posed to me in an interview.Question is from Conductors topic in portion Electric Fields in Material Space of Electromagnetic Theory
Answer» The CORRECT answer is (c) 1000 Explanation: The CONDUCTION current DENSITY is given by, J = σE J = 500 X 2 = 1000 units.

57.	For conductors, the free electrons will exist at(a) Valence band(b) Middle of valence and conduction band(c) Will not exist(d) Conduction bandI have been asked this question in an international level competition.The question is from Conductors in chapter Electric Fields in Material Space of Electromagnetic Theory
Answer» RIGHT choice is (d) CONDUCTION band Explanation: In conductors, the free electrons exist in the conduction band. Since the band gap energy is very low, LESS energy is required to transport the free electrons to the conduction band, as they are readily available to CONDUCT.

58.	The current in a metal at any frequency is due to(a) Conduction current(b) Displacement current(c) Both conduction and displacement current(d) Neither conduction nor displacement currentThe question was asked in my homework.I would like to ask this question from Conductors topic in section Electric Fields in Material Space of Electromagnetic Theory
Answer» The correct option is (a) Conduction current Explanation: At any frequency, the current through the METAL will be DUE to conduction current. Only at HIGH frequencies and when medium is air, the conduction is due to displacement current. Thus in GENERAL the current in metal is due to conduction current, which depends on the mobility of the carriers.

59.	Find the band gap energy when a light of wavelength 1240nm is incident on it.(a) 1eV(b) 2eV(c) 3eV(d) 4eVThis question was addressed to me during an interview.This interesting question is from Conductors in division Electric Fields in Material Space of Electromagnetic Theory
Answer» Correct answer is (a) 1eV The best explanation: The BAND GAP ENERGY in electron volt when WAVELENGTH is given is, Eg = 1.24(μm)/λ = 1.24 x 10^-6/1240 x 10^-9 = 1eV.

60.	Alternating current measured in a transmission line will be(a) Peak value(b) Average value(c) RMS value(d) ZeroI had been asked this question in an online interview.Asked question is from Conductors in section Electric Fields in Material Space of Electromagnetic Theory
Answer» Correct option is (C) RMS value To explain I WOULD say: The INSTANTANEOUS CURRENT flowing in a transmission line, when measured using an ammeter, will give RMS current value. This value is 70.7% of the peak value. This is because, due to oscillations in AC, it is not possible to measure peak value. Hence to normalise, we consider current at any time in a line will be the RMS current.

61.	Conduction in metals is due to(a) Electrons only(b) Electrons and holes(c) Holes only(d) Applied electric fieldThe question was asked in my homework.Enquiry is from Conductors topic in portion Electric Fields in Material Space of Electromagnetic Theory
Answer» Correct OPTION is (a) ELECTRONS only For EXPLANATION I WOULD SAY: Conduction in metals is only due to majority carriers, which are electrons. Electrons and holes are responsible for conduction in a semiconductor.

62.	Find the range of band gap energy for conductors.(a) >6 eV(b) 0.2-0.4 eV(c) 0.4-2 eV(d) 2-6 eVI had been asked this question in examination.My question comes from Conductors in portion Electric Fields in Material Space of Electromagnetic Theory
Answer» RIGHT CHOICE is (B) 0.2-0.4 eV The explanation: CONDUCTORS are MATERIALS with least band gap energy. The smallest range in this group is 0.2-0.4 eV.

63.	Which of the following are conductors?(a) Ceramics(b) Plastics(c) Mercury(d) RubberI had been asked this question in a national level competition.The doubt is from Conductors topic in portion Electric Fields in Material Space of Electromagnetic Theory
Answer» The correct OPTION is (c) Mercury Best explanation: Normally, metals are said to be GOOD conductors. Here mercury is the only METAL (which is in liquid FORM). The other OPTIONS are insulators.