Semiconductor Electronics-Materials, Devices and Simple Circuits Mock Test – Class 12 Physics

1. In a junction transistor, the three terminals are:

2. A diode is marked with a band near one terminal in a practical package. In many common diode packages, the banded end indicates the:

3. A doped semiconductor is useful in devices mainly because doping allows:

4. A single gate has both inputs connected to . If , the output is:

5. The statement “logic gates are made only from mechanical switches and not from semiconductor devices” is unsuitable because:

6. A two-input gate has inputs and . Its output is:

7. An transistor has its emitter-base junction forward biased and collector-base junction reverse biased. If the base is made accidentally much thicker than usual, the likely effect is:

8. A Zener regulator is fed from through . The load current varies from to . The range of Zener current is approximately:

9. In a doped semiconductor, a rise in temperature usually affects minority carriers noticeably because:

10. A two-input logic gate has output only for and . Its Boolean expression is:

11. The intrinsic carrier concentration represents:

12. A - junction is intended for controlled operation in reverse breakdown at nearly constant voltage. The most suitable device is:

13. A -type semiconductor is electrically neutral even though holes are majority carriers. The best explanation is:

14. A graph compares diffusion current and drift current magnitudes during formation of a - junction. At equilibrium, the graph should show:

15. In the input characteristic of a common-emitter transistor, the graph is generally drawn between:

16. A silicon diode and a germanium diode are compared through their forward characteristics. The germanium curve begins its steep rise at a lower voltage mainly because:

17. A doped semiconductor has , but the sample is electrically neutral overall. The best reason is:

18. An intrinsic semiconductor has , , and conductivity . After heating, becomes , becomes half, and becomes times its original value. The new conductivity is:

19. A material has equal electron and hole concentrations, but electron mobility is greater than hole mobility. Its electron contribution to conductivity is:

20. In a transistor amplifier, the output signal energy ultimately comes mainly from:

21. A graph of a diode characteristic shows a steep current rise for positive voltage near , a small nearly constant current for moderate negative voltage, and a sharp rise at large negative voltage. The best interpretation is:

22. A logic circuit has output . The output for and is:

23. A transistor used as a switch is in cut-off when it behaves approximately like:

24. A full-wave bridge rectifier is supplied from a secondary with . Each conducting silicon diode drops . A capacitor charges approximately to the peak load voltage. The approximate capacitor voltage is:

25. In an energy-band description of a solid, the valence band mainly refers to:

26. A diode under reverse bias suddenly carries a very large current when the reverse voltage is made high enough. The most suitable description is:

27. Consider the following statements about carrier currents.
I. Electron motion and conventional current are in opposite directions.
II. Hole motion and conventional current are in the same direction.
III. Fixed ion motion is the main source of drift current in ordinary semiconductor conduction.
The valid statements are:

28. A graph is described for a reverse-biased diode.

The nearly flat part of the graph represents:

29. The forbidden energy gap represents the energy needed for an electron to move:

30. A silicon sample has much larger than . Based only on carrier concentrations, this sample should not be called intrinsic because:

31. A claim says: “Reverse bias blocks a diode because no carriers of any kind exist in the semiconductor.” The best evaluation is:

32. A claim says: “A transistor is just two separate diodes connected back-to-back, so it should work the same way as two ordinary diodes.” The claim is:

33. A Zener regulator has , , , and . If the Zener is regulating, the Zener current is:

34. In a photodiode, increasing the incident light intensity generally causes:

35. Read the situation below.

The semiconductor formed is best described as:

36. A semiconductor at a fixed temperature is doped so that electrons dominate the conduction with . If the hole contribution is negligible, , and , the conductivity is closest to:

37. A device is required to allow current mainly in one direction in a simple circuit. The most suitable semiconductor device for this basic role is a:

38. A crystal has a filled valence band and an empty conduction band separated by a small energy gap. What change is most directly needed for it to show electronic conduction?

39. A transistor has , , and . If , the active-region estimate gives , but saturation current allowed by the load is:

40. Compared with a half-wave rectifier using the same input frequency, a full-wave rectifier gives:

41. A compact electronic module contains thousands of transistors and interconnections formed on one small silicon chip. This is best described as:

42. In a common-emitter transistor circuit, the input is usually applied between:

43. A -type semiconductor has , and all acceptors are ionised. If holes dominate conduction, , and , the conductivity is closest to:

44. The unit pair most suitable for and is:

45. The Fermi level of an intrinsic semiconductor is described qualitatively as lying:

46. The Boolean expression for a two-input gate is:

47. The Boolean expression simplifies to:

48. In a text-described band diagram, Material has overlapping valence and conduction bands, Material has , and Material has a very large . The most reasonable classification is:

49. Read the passage below.

The process occurring near the boundary is:

50. Study the table for a pure semiconductor at two temperatures.

Assuming mobilities do not change appreciably, the expected comparison is: