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 ___ ?

29. In semiconductors, at room temperature ___ ?

28. The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is10 V. The d.c component of the output voltage is ?

27. In a p − n junction photocell, the value of the photo-electromotive force produced by monochromatic light is proportional to ?

26. If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be ?

25. Barrier potential of a p − n junction diode does not depend on ___ ?

24. Reverse bias applied to a junction diode ___ ?

23. A d.c. battery of V volt is connected to a series combination of a resistor R and an ideal diode D as shown in the figure below. The potential difference across R will be ?

23. A d.c. battery of V volt is connected to a series combination of a resistor R and an ideal diode D as shown in the figure below. The potential difference across R will be ?

22. In a p − n junction ___ ?

21. The intrinsic semiconductor becomes an insulator at ___ ?