SECTION-3
ENGINEERING MATERIAL OBJECTIVE QUESTIONS/MCQ
 
Q11. The semi-conduction produced by holes due to impurity atoms is known as
(a) extrinsic semi-conduction 
(b) intrinsic semi-conduction 
(c) both (a) and (b) 
(d) none of the above. 
Ans: (a) extrinsic semi-conduction
Q12. A p–n junction is
(a) an amplifier 
(b) a rectifier 
(c) an insulator 
(d) none of the above.
Ans: (b) a rectifier
Q13. No external battery is required in
(a) photo conductive cell 
(b) photo voltage cell 
(c) photo emissive cell 
(d) all of the above. 
Ans: (b) photo voltage cell
Q14. The mobility of holes is
(a) more than that of electrons 
(b) equal to that of electrons 
(c) less than that of electrons 
(d) none of the above.
Ans: (c) less than that of electrons
Q15. In donor impurities are introduced into one side and acceptor into the other side of a single crystal of silicon or germanium,
(a) a transistor is formed 
(b) a p–n junction is formed 
(c) a photo cell is formed 
(d) none of the above. 
Ans: (b) a p–n junction is formed
Q16. In case of p–n junction (rectifier), donor ions are represented by
(a) minus sign 
(b) plus sign 
(c) no sign 
(d) both plus and minus sign.
Ans: (b) plus sign
 
Q17. When the p-side of the p–n junction is positive with respect to the n-side and the applied voltage is more than the barrier voltage, the junction behaves like a
(a) closed switch 
(b) open switch 
(c) open or closed switch 
(d) none of the above. 
Ans: (a) closed switch
Q18. The p–n junction has
(a) a very large resistance in the forward and opposite directions 
(b) a very small resistance in the forward and opposite direction 
(c) a very large resistance in forward direction and a very small resistance in opposite direction 
(d) a very small resistance in the forward direction and a very large resistance in the opposite direction.
Ans: d) a very small resistance in the forward direction and a very large resistance in the opposite direction.
Q19. Photo cells are employed for converting
(a) mechanical energy into electrical energy 
(b) electrical energy into mechanical energy 
(c) electrical energy into radiation energy 
(d) radiation energy into electrical energy. 
Ans: (d) radiation energy into electrical energy.
Q20. The photo-emission starts only when the frequency of the incident radiations
(a) is less than the threshold frequency 
(b) is equal to the threshold frequency 
(c) is more than the threshold frequency 
(d) none of the above.
Ans: (d) none of the above.
 
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Each section contains maximum 80 Questions. To practice more questions visit other sections.
 
Engineering Material Objective Questions – Section-1
 
Engineering Material Objective Questions – Section-2
 
Engineering Material Objective Questions – Section-3
 
Engineering Material Objective Questions – Section-4
 
Engineering Material Objective Questions – Section-5
 
 

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