1. Materials whose conductivity lies between conductors and insulators are
Answer: A. semiconductors
Physics Class 10 Unit 18: Electronics MCQs
82 multiple choice questions with the correct answer for each. Tap an option to check yourself, or switch on "Show all answers". This is page 1 of 2.
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2. Pure semiconductors are called
Answer: B. intrinsic semiconductors
3. Semiconductors doped with specific impurities are called
Answer: C. extrinsic semiconductors
4. When a pentavalent impurity is added to silicon, the result is
Answer: D. n-type semiconductor
5. When a trivalent impurity is added to silicon, the result is
Answer: B. p-type semiconductor
6. A pentavalent impurity has ______ valence electrons.
Answer: D. five
7. A vacant spot in a covalent bond is called a
Answer: C. hole
8. The majority charge carriers in an n-type semiconductor are
Answer: A. electrons
9. The majority charge carriers in a p-type semiconductor are
Answer: B. holes
10. Pentavalent impurities are called donors because they
Answer: D. donate free electrons
11. Trivalent impurities are called acceptors because they
Answer: A. accept electrons creating holes
12. The region near the junction that is free of mobile charges is the
Answer: C. depletion region
13. The potential barrier for a germanium crystal is about
Answer: B. 0.3 V
14. The potential barrier for a silicon crystal is about
Answer: C. 0.7 V
15. A PN junction diode allows current to pass in
Answer: A. one direction only
16. A PN junction diode is used as a
Answer: D. rectifier
17. The biasing in which the diode allows current to flow is called
Answer: B. forward bias
18. A diode is forward biased when the positive terminal of the DC source is connected to the
Answer: A. p-type
19. In forward bias, the depletion region
Answer: C. decreases in width
20. In forward bias, the barrier potential
Answer: D. is reduced
21. When the potential at the anode (p-type) is smaller than at the cathode (n-type), the diode is
Answer: A. reverse biased
22. In reverse bias, the depletion region
Answer: D. becomes wider
23. In reverse bias, only a small current flows due to
Answer: C. minority charge carriers
24. The small current in reverse bias is of the order of a few
Answer: B. microamperes
25. The small current in a reverse-biased diode is called
Answer: D. reverse or leakage current
26. A light-emitting diode (LED) emits light when it is
Answer: B. forward biased
27. In an LED, when electrons fall into holes, they
Answer: C. radiate energy as light
28. A transistor is a ______ terminal device.
Answer: A. three
29. The three terminals of a transistor are
Answer: A. emitter, base and collector
30. A transistor is a ______ device because both holes and electrons participate in conduction.
Answer: D. bipolar
31. The two types of transistors are
Answer: C. PNP and NPN
32. An NPN transistor is made by joining
Answer: B. one p-type between two n-types
33. A PNP transistor is made by sandwiching
Answer: B. an n-type between two p-types
34. The heavily doped region of a transistor is the
Answer: D. emitter
35. The base of a transistor is
Answer: A. thin and lightly doped
36. The function of a transistor is to
Answer: C. amplify current
37. In normal operation of an NPN transistor, the emitter-base junction is
Answer: D. forward biased
38. In normal operation of an NPN transistor, the collector-base junction is
Answer: C. reverse biased
39. The relation between emitter, collector and base currents is
Answer: B. IE = IC + IB
40. The current gain β of a transistor is given by
Answer: A. IC/IB
41. The current gain α of a transistor is given by
Answer: A. IC/IE
42. The majority charge carriers in the emitter of an NPN transistor are
Answer: C. electrons
43. In a junction transistor, IC = 99.9 mA and IB = 0.1 mA. The emitter current is
Answer: B. 100 mA
44. If IE = 1 mA and IC = 0.25 mA, the base current IB is
Answer: D. 0.75 mA
45. In a junction transistor, IE = 5.82 mA and IB = 120 µA. The collector current is
Answer: C. 5.7 mA
46. For IB = 600 µA and IC = 30 mA, the current gain β is
Answer: D. 50
47. For IC = 150 mA and β = 190, the base current required is about
Answer: B. 0.8 mA
48. When the emitter current changes by 4 mA and the collector current by 3.5 mA, β is
Answer: A. 7
49. The transistor was developed in 1948 at
Answer: C. Bell Laboratories
50. The transistor invention was awarded the Nobel Prize in Physics in
Answer: D. 1956
About Physics Class 10 Unit 18 MCQs (Federal Board)
These 82 Physics MCQs cover Class 10 Unit 18: Electronics of the Federal Board (FBISE) SSC-II (Class 10) syllabus. They are SLO-based MCQs as per the new pattern for FBISE exams. Each question has four options and the correct answer is shown, so you can practise for the annual examination and find the topics you still need to revise. The questions are split over 2 pages of 50. You can also read the Electronics notes for this chapter. Download the Electronics MCQs as a PDF using the button at the top of this page.