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

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

2. A common-emitter amplifier is biased at a proper operating point before applying the signal. The main reason is to:

3. Two samples contain equal numbers of mobile majority carriers: sample is -type and sample is -type. The charge-balancing fixed ions are:

4. A Zener regulator has , , , and . The Zener current is:

5. A graph of a Zener diode shows a nearly vertical reverse-breakdown region at . This part of the graph is useful for regulation because:

6. Use the graph description below.

The steep rise of the curve indicates:

7. Consider the following statements about intrinsic conductivity.
I. Electrons and holes both contribute to conductivity.
II. For intrinsic material, .
III. In the intrinsic conductivity formula, electron and hole mobility contributions are subtracted.
The valid statements are:

8. A gate has input . Its output is:

9. A device is needed for automatic switching of a street light when the surrounding light level changes. The most suitable semiconductor device from the given choices is:

10. A Zener diode rated at carries in breakdown. Its power dissipation is:

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

The nearly flat part of the graph represents:

12. Study the truth table.

The logic gate represented is:

13. Use the arrangement described below.

After this electron movement, the hole is effectively located:

14. A newly formed - junction reaches equilibrium when:

15. A transistor amplifier receives a sinusoidal input, but the output waveform has flattened tops. The most likely reason is:

16. An has photon wavelength and operates at current with forward drop . Taking , the electrical power input and photon energy are closest to:

17. A circuit designer wants an output only when a light sensor signal and an enable signal . The sensor output is from a photodiode circuit, and the final switching device is a transistor. The suitable logic relation and transistor state for are:

18. A forward-biased diode shows only a very small current at first and then a rapid rise after a certain voltage. This happens because:

19. In a silicon diode circuit, a battery, a resistor, and two forward-biased silicon diodes are in series. Taking each silicon diode drop as , the circuit current is:

20. Static resistance of a diode at a particular operating point is calculated using:

21. A rectifier connected to a source gives output pulses at . The rectifier is most likely:

22. In a common-emitter amplifier, the negative sign of voltage gain indicates:

23. Assertion: The conductivity of a semiconductor generally increases with temperature.
Reason: Heating a semiconductor can generate additional electron-hole pairs.

24. Assertion: In active operation, a transistor can use a small base current to control a much larger collector current.
Reason: The thin base allows most carriers injected by the emitter to reach the collector.

25. A bridge rectifier uses silicon diodes and is supplied by a transformer secondary with peak voltage . If two diodes conduct in each half-cycle and each has a drop of , the approximate peak voltage across the load before filtering is:

26. In a half-wave rectifier, if the diode is forward biased during the positive half-cycle of the input, the load output appears:

27. In the relation , the term represents the contribution associated with:

28. Read the passage below.

The event described in the passage produces:

29. An ideal diode model is used only for a first approximation. In that model, a forward-biased diode is treated as:

30. A transistor has , , and . If , the active-region estimate and load-limited saturation current imply:

31. The intrinsic carrier concentration represents:

32. A claim says: “A full-wave rectifier must always use a centre-tapped transformer.” The best evaluation is:

33. The base of a transistor is made thin and lightly doped mainly so that:

34. The output of a two-input gate is when:

35. A transistor circuit uses the collector terminal as the common terminal. The input signal is applied between base and collector, and the output is taken between emitter and collector. The configuration is best identified as:

36. Consider the following statements about basic logic gates.
I. An gate gives output only when all inputs are .
II. An gate gives output when at least one input is .
III. A gate requires two inputs to invert a signal.
The valid statements are:

37. In a pure silicon crystal, each silicon atom forms covalent bonds with neighbouring silicon atoms. This bonding is important because it:

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

39. A transistor used as a switch is in saturation when it behaves approximately like:

40. A hole in a semiconductor is best understood as:

41. A transistor switch has . Neglecting leakage, the collector current is expected to be:

42. In an intrinsic semiconductor, the conductivity is due to:

43. A bridge rectifier differs from a centre-tapped full-wave rectifier mainly because a bridge rectifier:

44. Use the circuit description below.

The final output is:

45. The statement “an intrinsic semiconductor conducts only by electrons” is incomplete because:

46. A passage describes a modified silicon crystal.

The impurity action described here is best identified as:

47. A Zener diode has a maximum power rating of . The maximum safe Zener current is:

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

49. A common-emitter amplifier has . A small input signal causes to decrease by . The collector voltage change is:

50. Under reverse bias, the depletion region of a - junction: