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.Management Sciences
Category: Electrical Engineering Materials
Thermonic emission occurs in______________?
A. vacuum tubes
B. copper conductors
C. ferrite cores
D. transistors
Super conductivity can be destroyed by_____________?
A. adding impurities
B. reducing temperatures
C. application of magnetic field
D. any of the above
The carbon percentage is least in__________________?
A. low carbon steel
B. wrought iron
C. cast iron
D. malleable iron
is an element used in semiconductors whose atoms have three valence electrons?
A. An acceptor
B. A donor
C. Germanium
D. Silicon
The conductors have transport phenomena of electrons due to____________?
A. electric field
B. magnetic field
C. electromagnetic field
D. none of the above
The current due to electron flow in conduction band is the hole current in valence band?
A. equal to
B. less than
C. greater than
D. any of the above
Mercury as an electric contact material is_______________?
A. a liquid
B. a metal
C. a metal liquid
D. a gas
Carbon resistors are used extensively because they are____________?
A. easy to make
B. compact
C. inexpensive
D. all of the above reasons
Copper, even though costly, finds use in the windings of electrical machines because_____________?
A. copper points offer low contact resistance
B. copper can be easily soldered and welded
E. copper windings are less bulky and the machines become compact
D. all of the above
Which of the following is a semiconductor material ?
A. Phosphorous
B. Rubber
C. Silicon
D. Aluminium
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