14. SEMI CONDUCTOR ELECTRONICS : ATERIALS, DEVICES & SIMPLE CIRCUITS( Objective Question Answer 2022 )

1. Bonds in a semiconductor :

(A) trivalent
(B) covalent
(C) bivalent
(D) monovalent

2. Number of electrons in the valence shell of a semiconductor is :

(A) 1
(B) 2
(C) 3
(D) 4

3. Semiconductors of both p-type and n-type are produced by :

(A) ionic solids
(B) covalent solids
(C) metallic solids
(D) molecular solids

4. With fall of temperature, the forbidden energy gap of a semiconductor

(A) increases
(B) decreases
(C) remains unchanged
(D) sometimes increases and sometimes decreases

5. In a p-type semiconductor, current conduction is by :

(A) atoms
(B) holes
(C) electrons
(D) protons

6. The relation between number of free electrons (n) in a semiconductor and temperature (T) is given by :

(A) n ∝ T
(B) n ∝ T²
(C) n ∝ T^1/2
(D) n ∝ T^3/2

7. In reverse biasing :

(A) large amount of current flows
(B) no current flows
(C) potential barrier across junction increases
(D) depletion layer resistance increases

8. Main function of a transistor is to :

(A) rectify
(B) simplify
(C) amplify
(D) all the above

9. In semi conductor, at room temperature :

(A) the valence bond is partially empty and the conduction band is partially filled
(B) the valence band is completely filled and the conduction band is partially filled
(C) the valence band is completely filled
(D) the conduction band is completely empty

10. Crystal diode is :

(A) amplifying device
(B) fluctuating device
(C) non-linear device
(D) linear device

11. The part of a transistor which is heavily doped to produce a large number of majority carriers is :

(A) base
(B) emitter
(C) collector
(D) None of these

12. A p-type semiconductor is :

(A) negatively charged
(B) positively charged
(C) uncharged
(D) None of these

13. In n_e, n_h, n_t, N_d and N_a respectively denote number density of electrons, number density of holes, number density of intrinsic carriers, density of donor atoms, density of acceptor atoms in a semiconductor, we can write :

(A) n_en_h = n_i²
(B) n_en_h = n_i
(C) n_en_i = n_h
(D) n_en_i = (n_e + n_i)n_h

14. Refer to previous question :

(A) n_e = N_d >> n_h
(B) n_h = N_a = n_e
(C) n_h = N_d + N_a = n_e
(D) n_en_h = N_dN_a

15. The ‘device used to convert“ alternating voltage/current into direct voltage/current is called :

(A) rectifier
(B) amplifier
(C) oscillator
(D) None of these

16. If nh and ne are the number of holes and electrons, is an intrinsic semiconductor :

(A) n_h > n_e
(B) n_h = n_e
(C) n_h > n_e
(D) h_h ≠ E_n

17. Band gap in germanium and silicon is eV are :

(A) 0.78, 1.17
(B) 1.1, 0.7
(C) 11,0
(D) 0,1,1

18. In a common base configuration of a transistor   then; current gain in common emitter configuration of transistor will be :

(A) 49
(B) 98
(C) 4.9
(D) 24.5

19. The correct relation between the two current gains ∝ and β in a transistor is :

Class 12th physics objective question in English