c-dac electronics sample papers,microprocessor mcq question papers,c-dac electronics study materials,

Center for Development of Advanced Computing

C-DAC Project Engineers

Electronics & Communication Engineering

Q.1.Which of the following pairs does-not match?

• Dielectric strength of air 3 to 5 kV/mm
• Vacuum may be used for reflective insulation of liquid O2 tank
• Permissible water content in transformer oil is 50 ppm
• Carbon-pile resistors for insulation of oil-filled cables

Q.2.Memory of a computer can be increased by

• increasing the magnetic bubble diameter
• decreasing the magnetic bubble diameter
• using adomax, a recent hard magnetic material
• using strontium titanate (Sr Ti O3)

Q.3.The residual magnetic flux density is more in

• metallic magnets
• ceramic magnets
• graphite
• iron oxide

Q.4.Manganese ferrites is a 1:1 mixture of

• MnO and CdO
• MnO and Fe2O3
• MnCl2 and Fe2O3
• MnCl2 and CdO

Q.5.High frequency transformer cores are generally made of

• Cast iron
• Mumetal
• Ferrite
• Graphite

Q.6.For high speed reading and storing of information in a computer, the use is made of

• ferrite
• piezoelectric
• pyroelectrics
• ferromagnetics above 7680 C

Q.7.The poles of alternators are usually made of

• wrought iron
• permalloy
• CdS
• alnico

Q.8.In a semi-conductor strain gauge, the change in resistance on application of strain is mainly due to the change in its

• lenght
• diameter
• resistivity
• length and diameter

Q.9.Transformer oil is a liquid insulator and is mainly used in transformer.It is filled into transformer tank to serve the following purposes:
I. To transfer the heat generated inside the transformer core and windings, to the outer cooling surfaces.
II. To main insulation in the primary and secondary windings.

• Only I is correct
• Only II is correct
• Both I and II are correct
• None of these

Q.10.Electrons in an atom may be visualized by

• spectroscopic techniques
• radiography
• optical microscope
• etching techniques

Q.11.Most malleable metal is

• Au
• Ag
• Cr
• Osmium

Q.12.As the temperature of a p-type semi-conductor is gradually and continuously increased, the fermi level will move

• into the valence band
• into the conduction band
• towards the middle of the forbidden gap
• into the region between the acceptor level and the valence band

Q.13.Which one of the following polarization mechanisms/sets of mechanisms contribute to the static dielectric constant of a homo-polar neutral dielectric?

• Electronic
• Electronic and ionic
• Electronic, ionic and dipolar
• Electric and dipolar

Q.14.Consider the following materials:
1. Pure silica
2. Bakelite
3. Hard rubber
4. Paraffin
The correct sequence of the DECREASING order of loss angles (60 Hz) of these dielectric materials is

• 1,2,3,4
• 1,4,3,2
• 4,1,2,3
• 4,3,1,2

Q.15.Which one of the following materials is piezoelectric?

• Pb2 Au
• BaTiO3
• MgAl2O4
• NiFe2O4

Q.16.The residual resistivity of metals

• is essentially independent of temperature
• increases linearly with increasing temperature
• decrease linearly with increasing temperature
• initially increase linearly with temperature and then remains constant

Q.17.Consider the following metals: 1. Zinc 2. Gold 3. Silver 4. Copper The correct sequence of the increasing order of their resistivities is

• 4,3,1,2
• 3,4,2,1 (Ans)
• 4,3,2,1
• 3,4,1,2

Q.18.A type-I super-conductor maintained at a temperature T < Tc is subject to a magnetic field H < Hc. The superconductor will exhibit.

• perfect diamagnetism
• partial diamagnetism
• perfect paramagnetism
• partial paramagnetism

Q.19.The magnetic susceptibility of a paramagnetic material is

• less than zero
• less than one but positive
• greater than one
• equal to zero

Q.20.Magnetostriction is a phenomenon whereby the magnetisation of a ferromagnetic material leads to a change in

• relative permeability
• physical dimensions
• spontaneous magnetisation
• magnetic susceptibility

Q.21.Two initially identical samples A and B of pure germanium are doped with donors to concentrations of 1*1020 m-3 and 3*1020  m-3 respectively. If the hole concentration in  A is 9*1012 m-3, then the hole concentration in B at the same temperature will be

• 3*1012 m-3
• 7*1012 m-3
• 11*1012 m-3
• 27*1012 m-3

Q.22.Consider the following statements :Pure germanium and pure silicon are examples of 1.  Direct band-gap semi-conductors 2.  Indirect band-gap semi-conductors 3. Degenrate semi-conductors of these statements

• 1 alone is correct
• 2 alone is correct
• 3 alone is correct
• 1 and 3 are correct

Q.23.Consider the following statements : In a semi-conductor, the measurement of Hall co-efficient provides quantitative information on 1. Density of carriers 2. Polarity of carriers 3. Effective mass of the carriers 4. Mobility of the carriers Of these statements :

• 1 and 2 are correct
• 2 and 3 are correct
• 1 and 3 are correct
• 1,2,3 and 4 are correct

Q.24.Silicon carbide reinforced aluminum metal matrix composites find application in

• the manufacture of transformer cores
• the manufacture of cutting tools
• the manufacture of standard resistors
• aerospace industry

Q.25.GaAs LEDs emit radiation in the

• ultra-violet region
• violet-blue-green range of the visible region
• visible region
• infra-red region

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