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

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

2. A photodiode has responsivity at a certain wavelength. Its dark current is . If the incident optical power is , the total reverse current is:

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

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

5. A graph is drawn for an intrinsic semiconductor with on the vertical axis and on the horizontal axis, while and are constant. The graph should be:

6. Assertion: A solar cell and a photodiode both involve light-generated electron-hole pairs.
Reason: Their circuit use is identical because both must be operated in reverse breakdown.

7. An of forward drop is connected to a supply through a resistor. The desired current is . The nearest suitable series resistance is:

8. A note in a circuit file says: “Apply a bias voltage across the semiconductor device before observing its current.” Here, bias voltage means:

9. In digital circuits, a transistor used as a switch represents logic and logic by using:

10. The Boolean expression simplifies to:

11. A transistor has . The corresponding value of is closest to:

12. A heavily doped - junction generally undergoes Zener breakdown at relatively low reverse voltage because:

13. A semiconductor has carrier concentration increasing from to when temperature is raised. If mobility and sample geometry are assumed unchanged, the conductivity changes approximately by:

14. A logic expression can be simplified to:

15. The acceptor energy level in a -type semiconductor is generally shown:

16. A centre-tapped full-wave rectifier uses silicon diodes. In one half-cycle, only one diode is in the conducting path. If the secondary half-winding peak voltage is , the approximate peak load voltage is:

17. A capacitor filter is connected across the load after a rectifier. Its main function is to:

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

19. For a transistor to operate in the active region, the usual biasing condition is:

20. The SI unit of electric current is:

21. In the band picture of an -type semiconductor, the donor level is usually located:

22. Consider two statements about temperature effects.
I. In metals, increased temperature usually increases electron scattering.
II. In semiconductors, increased temperature usually increases the number of electron-hole pairs.
III. In semiconductors, increased temperature usually makes the forbidden gap act as a conducting wire.
The valid statements are:

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

24. The Boolean expression simplifies to:

25. For an intrinsic semiconductor, the conductivity relation may be written as:

26. A common-emitter amplifier has , collector load , and input resistance . Ignoring phase sign for magnitude, the approximate voltage gain using is:

27. A claim says: “In the active region, the collector-base junction is reverse biased, so no carrier can cross into the collector.” The claim is:

28. A common-emitter output curve is nearly horizontal in the active region. This means:

29. A two-input gate gives output for:

30. Under forward bias, the depletion region of a - junction:

31. In a bridge rectifier, the number of diodes conducting during each half-cycle is usually:

32. Read the situation below.

The most reasonable identification is:

33. A full-wave rectifier is designed so that the current through the load:

34. The output of a basic rectifier without a filter is best described as:

35. A device is required to detect weak light, another device must emit light, and a third must supply electrical energy from sunlight. The correct order is:

36. A single gate is used with both inputs connected to the same signal . If , the output is:

37. A photodiode has dark current . Its photocurrent is per unit light-intensity level. If the measured reverse current is , the light-intensity level is:

38. In an , the colour of emitted light is mainly determined by:

39. The conventional current through a forward-biased diode is usually taken to flow:

40. A silicon sample is first intrinsic and then doped with a small amount of arsenic. After doping, its conductivity increases mainly because:

41. A transistor has two - junctions because:

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

43. A qualitative energy-band diagram shows an impurity level just above the valence band and the Fermi level nearer the valence band. The material is best interpreted as:

44. A semiconductor and an insulator are both heated slightly from room temperature. The semiconductor shows a much more noticeable conductivity increase because:

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

46. A material has electrical conductivity greater than that of an insulator but smaller than that of a good conductor. The material is best classified as a:

47. A comparison between intrinsic and extrinsic semiconductors is made in the following table.

The mismatched row is:

48. Study the resistance comparison table.

The row that is not suitable is:

49. A logic circuit has output . For and , the output is:

50. A completed statement about an intrinsic band picture is: “The forbidden energy gap is called forbidden because ______.”