49. In a n-type semiconductor, which of the following statement is true?

48. In an unbiased p − n junction, holes diffuse from the p-region to n-region because of ___ ?

47. Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is :

47. Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is :

46. C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor. This is because :

46. C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor. This is because :

(a) In case of C the valence band is not completely filled at absolute zero temperature.

(b) In case of C the conduction band is partly filled even at absolute zero temperature.

(c) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third.

(d) The four bonding electrons in the case of C lie in the third orbit, whereas for Si they lie in the fourth orbit.

Answer :  (c) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third.

45. In forward biasing of the p − n junction ___ ?

44. If a small amount of antimony is added to germanium crystal ___ ?

43. In the following figure, the diodes which are forward biased, are ?

42. Pure Si at 500 K has equal number of electron (ne) and hole (nh) concentrations of 1.5 × 1016 m−3 . Doping by indium increases nh to 4.5 × 1022 m−3 . The doped semiconductor is of ?

41. A zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is ?

41. A zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is ?

40. Which one of the following statement is FALSE ?

39. Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has high melting point ?

38. A p−n photodiode is fabricated from a semiconductor with a band gap of 2.5eV. It can detect a signal of wavelength ?

37. Sodium has body centred packing. Distance between two nearest atoms is 3.7Â. The lattice parameter is ?

36. A p-n photodiode is made of a material with a band gap of 2.0eV. The minimum frequency of the radiation that can be absorbed by the material is nearly ?

35. For a cubic crystal structure which one of the following relations indicating the cell characteristics is correct?

34. In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is ?

34. In the energy band diagram of a material shown below, the open circles and filled circles denote holes and electrons respectively. The material is ?

33. Choose the only false statement from the following

32. Carbon, silicon and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (Eg)C (ES)Si and (Eg)Ge respectively. Which one of the following relationships is true in their case ?

31. Application of a forward bias to a p−n junction ?

30. Zener diode is used for ___ ?