Q.1 The thermionic emission is due to which of the following?
A. high temperature
B. electromagnetic field
C. electrostatic field
D. all of the above
Ans.: A
Q. 2 The electric breakdown strength is affected by which of the following?
A. composition of materials
B. shape of the applied voltage waveform
C. steepness of the waveform of the applied voltage
D. all of the above
Ans.: D
Q.3 If the temperature is lowered, the resistivity of all normal metals___.
A. tends to constant
B. tends to zero
C. first increase and then decrease
D. any of the above
Ans.: B
Q. 4 By which method, polyethylene is produced?
A. addition polymerization
B. condensation
C. condensation polymerization
D. none of the above
Ans.: A
Q. 5 Dielectric strength of asbestos is ___.
A. 20- 25 kV/mm
B. 3-4.5 kV/mm
C. 40-45 kV/mm
D. 30-40 kV/mm
Ans.: B
Q. 6 Following method can be used for thermoplastic materials.
A. casting
B. compression moulding
C. calendaring
D. blow moulding
Ans.: C
Q. 7 Out of the following semi-conductor has highest melting point.
A. Silicon
B. Lead sulphide
C. Germanium
D. Gallium arsenide
Ans.: A
Q. 8 what is the unit of retentivity?
A. Weber
B. Weber/AT
C. Weber per square meter
D. Tesla
Ans.: C
Q. 9 The materials commonly used for photoconductive cells in the visible spectrum.
A. cadmium sulphide
B. selenium
C. thallic sulphide
D. any of the above
Ans.: D
Q. 10 Breakdown in dielectric may be due to which of the following reason?
A. thermal breakdown
B. electrical breakdown
C. electrochemical breakdown
D. all of the above
Ans.: D
Q. 11 What is resistivity of a supper conductor?
A. low
B. infinite
C. Zero
D. unity
Ans.: C
Q. 12 The hall Effect voltage in intrinsic silicon is ___.
A. zero
B. negative
C. positive
D. any of the above
Ans.: B
Q. 13 Carbon resistor contains___.
A. solid carbon granules
B. finely divided carbon black
C. pulverized coal
D. none of the above
Ans.: B
Q. 14 Which of the following is hardest substance?
A. Gold
B. Tungsten
C. Diamond
D. Platinum
Ans.: C
Q. 15 In cathode vacuum tube, which of the following material is used?
A. Thoriated tungsten
B. mixture of barium oxidestrontium
C. tungsten
D. Any of the above
Ans.: D