1. A semiconductor is formed by ........ bonds.
(i) covalent (ii) electrovalent (iii) co-ordinate (iv) none of the above
2. The most commonly used semiconductor is ........
(i) germanium (ii) silicon (iii) carbon (iv) None
3 A semiconductor has generally ........ valence electrons.
(i)2 (ii) 3 (iii)6 (iv) 4
4. The maximum number of electrons which the valence shell of an atom can have is
(a) 6
(b) 8
(c) 18
(d) 2
5. When a pentavalent impurity is added to a pure semiconductor, it becomes ........
(i) an insulator (ii) an intrinsic semiconductor (iii) p-type semiconductor (iv) n-type
semiconductor
6. Addition of pentavalent impurity to a semiconductor creates many ........
(i) free electrons (ii) holes (iii) valence electrons (iv) bound electrons
7. A pentavalent impurity has ........ valence electrons.
(i)3 (ii) 5 (iii)4 (iv) 6
8. An n-type semiconductor is ........ (i) positively charged (ii) negatively charged Electronics (iii)
electrically neutral (iv) none of the above
9. A trivalent impurity has ........ valence electrons. (i)4 (ii) 5 (iii)6 (iv) 3
10. Addition of trivalent impurity to a semiconductor creates many ........ (i) holes (ii) free
electrons (iii) valence electrons (iv) bound electrons
11. A hole in a semiconductor is defined as ........ (i) a free electron (ii) the incomplete part of an
electron pair bond (iii) a free proton (iv) a free neutron
12. As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor ...
(i) remains the same (ii) increases (iii) decreases (iv) none of the above
13. In a semiconductor, current conduction is due ........
(i) only to holes (ii) only to free electrons (iii) to holes and free electrons (iv) none of the above
14. The random motion of holes and free electrons due to thermal agitation is called ........
(i) diffusion (ii) pressure (iii) ionisation (iv) none of the above
15. A forward biased pn junction has a resistance of the ........
(i) order of Ω (ii) order of kΩ (iii) order of MΩ (iv) none of the above
16. The battery connections required to forward bias a pn junction are ........
(i) +ve terminal to p and −ve terminal to n (ii) −ve terminal to p and +ve terminal to n (iii) −ve
terminal to p and −ve terminal to n (iv) none of the above
17. A reverse biased pn junction has ........
(i) very narrow depletion layer (ii) almost no current (iii) very low resistance (iv) large current
flow
18. A pn junction acts as a ........
(i) controlled switch (ii) bidirectional switch (iii) unidirectional switch (iv) none of the above
19. A reverse biased pn junction has resistance of the........
(i) order of Ω (ii) order of kΩ (iii) order of MΩ (iv) none of the above
20. The leakage current across a pn junction is due to ........
(i) minority carriers (ii) majority carriers (iii) junction capacitance (iv) none of the above
21. With forward bias to a pn junction, the width of depletion layer ........
(i) decreases (ii) increases (iii) remains the same (iv) none of the above
22. The leakage current in a pn junction is of the order of ........
(i)A (ii) mA (iii) kA (iv) μA
23. In an intrinsic semiconductor, the number of free electrons ........
(i) equals the number of holes (ii) is greater than the number of holes (iii) is less than the number
of holes (iv) none of the above
24. Electronic distribution of an Si atom is
(a) 2, 10, 2
(b) 2, 8, 4
(c) 2, 7, 5
(d) 2, 4, 8.
25. Semiconductor materials have ................. bonds.
(a) ionic
(b) covalent
(c) mutual
(d) metallic.
26. The process of adding impurities to a pure semiconductor
is called
(a) mixing
(b) doping
(c) diffusing
(d) refining.
28. Electron-hole pairs are produced by
(a) recombination
(b) thermal energy
(c) ionization
(d) doping
29. When a P-N junction is formed, diffusion current causes
(a) mixing of current carriers
(b) forward bias
(c) reverse bias
(d) barrier potential.
30. The area within a semiconductor diode where no mobile current carriers exist when it is
formed is called .......... region.
(a) depletion
(b) saturation
(c) potential barrier
(d) space charge.
