ELECTROMAGNETIC WAVES
AND ELECTRONICS
1. Electromagnetic waves are:
a) Mechanical waves
b) Longitudinal waves
c) Transverse waves
d) Stationary waves
2. The production of electromagnetic waves, specifically radio waves, is achieved through:
a) Electromagnetic induction
b) Electric discharge
c) Magnetic resonance
d) Thermionic emission
3. Information is carried by electromagnetic waves through variations in their:
a) Amplitude
b) Wavelength
c) Frequency
d) Velocity
4. Modulation refers to the process of varying the _______ of an electromagnetic wave.
a) Amplitude
b) Wavelength
c) Frequency
d) Speed
5. Sidebands are the frequencies that lie:
a) Above the carrier frequency in modulation
b) Below the carrier frequency in modulation
c) Above and below the carrier frequency in modulation
d) Exactly at the carrier frequency
6. The reception of electromagnetic waves is accomplished by:
a) Antennas
b) Conductors
c) Insulators
d) Resistors
7. The band theory of solids describes the behavior of electrons in:
a) Conductors only
b) Insulators only
c) Semiconductors only
d) All types of solids
8. Semiconductors have a _______ number of valence electrons.
a) High
b) Low
c) Variable
d) Non-existent
9. Atomic binding in semiconductors is primarily achieved through:
a) Covalent bonding
b) Ionic bonding
c) Metallic bonding
d) Van der Waals forces
10. The preparation of semiconductors involves processes such as:
a) Deposition
b) Etching
c) Doping
d) All of the above
11. Doping in semiconductors involves the intentional introduction of impurities to alter their:
a) Conductivity
b) Transparency
c) Density
d) Hardness
12. Donor and acceptor are types of:
a) Impurities in semiconductors
b) Crystal structures in semiconductors
c) Lattice defects in semiconductors
d) Crystallographic planes in semiconductors
13. Crystallography is the study of:
a) Crystal structures
b) Crystal defects
c) Crystal growth
d) Crystal vibrations
14. The crystal lattice of a solid refers to its:
a) Atomic arrangement
b) Crystal size
c) Crystal shape
d) Optical properties
15. The unit cell is the _______ repeating unit of a crystal lattice.
a) Smallest
b) Largest
c) Most stable
d) Most complex
16. The p-n junction is a boundary between:
a) Two different crystals
b) Two different materials
c) Two different lattice structures
d) Two different energy levels
17. Biasing in a semiconductor diode refers to:
a) Applying a voltage across the diode
b) Removing impurities from the diode
c) Increasing the temperature of the diode
d) Adjusting the diode's size
18. The semiconductor diode acts as a rectifier by allowing current flow in:
a) One direction only
b) Two directions simultaneously
c) Any direction
d) None of the above
19. A half-wave rectifier allows current flow during:
a) Positive half-cycles of the input waveform
b) Negative half-cycles of the input waveform
c) Both positive and negative half-cycles of the input waveform
d) None of the above
20. Full-wave rectification using two diodes allows current flow during:
a) Positive half-cycles of the input waveform
b) Negative half-cycles of the input waveform
c) Both positive and negative half-cycles of the input waveform
d) None of the above
21. Photodiodes are semiconductor devices that convert:
a) Light energy into electrical energy
b) Electrical energy into light energy
c) Heat energy into electrical energy
d) Electrical energy into heat energy
22. Light Emitting Diodes (LEDs) emit light when:
a) An electric current is applied in the forward direction
b) An electric current is applied in the reverse direction
c) An electric current is applied in either direction
d) No electric current is applied
23. A solar cell converts _______ energy into electrical energy.
a) Thermal
b) Mechanical
c) Light
d) Chemical
24. A transistor is a three-layer semiconductor device composed of:
a) Two p-n junctions
b) Three p-n junctions
c) Four p-n junctions
d) Five p-n junctions
25. Transistors operate based on the behavior of:
a) Electrons only
b) Holes only
c) Both electrons and holes
d) Neutrons
26. The working of an NPN transistor involves:
a) Majority carriers being electrons
b) Majority carriers being holes
c) Equal number of electrons and holes
d) No majority carriers
27. Transistor characteristics include:
a) Input characteristics
b) Output characteristics
c) Transfer characteristics
d) All of the above
28. A transistor can be used as an amplifier by operating it in the _______ region.
a) Active
b) Saturation
c) Cutoff
d) Reverse
29. The term "active region" refers to:
a) The range of voltages where a transistor operates as an amplifier
b) The range of temperatures where a transistor operates effectively
c) The range of frequencies where a transistor can amplify signals
d) The range of time intervals where a transistor can switch states
30. The bandgap in a semiconductor determines its:
a) Conductivity
b) Transparency
c) Density
d) Hardness
31. The process of modulating a signal by varying its frequency is known as:
a) Frequency modulation
b) Amplitude modulation
c) Phase modulation
d) Pulse modulation
32. The process of modulating a signal by varying its amplitude is known as:
a) Frequency modulation
b) Amplitude modulation
c) Phase modulation
d) Pulse modulation
33. The process of modulating a signal by varying its percentage of modulation is known as:
a) Frequency modulation
b) Amplitude modulation
c) Phase modulation
d) Pulse modulation
34. Sidebands in modulation contain the _______ of the modulating signal.
a) Amplitude
b) Frequency
c) Phase
d) Duration
35. Which of the following is NOT a type of modulation?
a) FM modulation
b) AM modulation
c) PM modulation
d) PC modulation
36. A crystal lattice is a regular _______ arrangement of atoms.
a) Random
b) Irregular
c) Periodic
d) Chaotic
37. A unit cell is the basic _______ of a crystal lattice.
a) Atom
b) Molecule
c) Group
d) Building block
38. In a p-n junction diode, forward biasing involves:
a) Applying a positive voltage to the p-side and negative voltage to the n-side
b) Applying a negative voltage to the p-side and positive voltage to the n-side
c) Applying a positive voltage to both the p-side and n-side
d) Applying a negative voltage to both the p-side and n-side
39. In a p-n junction diode, reverse biasing involves:
a) Applying a positive voltage to the p-side and a negative voltage to the n-side
b) Applying a negative voltage to the p-side and a positive voltage to the n-side
c) Applying a positive voltage to both the p-side and n-side
d) Applying a negative voltage to both the p-side and n-side
40. Transistors are commonly used in electronic devices for functions such as:
a) Amplification
b) Switching
c) Oscillation
d) All of the above
ANSWER KEY:
1. c) Transverse waves
2. b) Electric discharge
3. d) Velocity
4. a) Amplitude
5. c) Above and below the carrier frequency in modulation
6. a) Antennas
7. d) All types of solids
8. c) Variable
9. a) Covalent bonding
10. d) All of the above
11. a) Conductivity
12. a) Impurities in semiconductors
13. a) Crystal structures
14. a) Atomic arrangement
15. a) Smallest
16. b) Two different materials
17. a) Applying a voltage across the diode
18. a) One direction only
19. a) Positive half-cycles of the input waveform
20. c) Both positive and negative half-cycles of the input waveform
21. a) Light energy into electrical energy
22. a) An electric current is applied in the forward direction
23. c) Light
24. a) Two p-n junctions
25. c) Both electrons and holes
26. a) Majority carriers being electrons
27. d) All of the above
28. a) Active
29. a) The range of voltages where a transistor operates as an amplifier
30. a) Conductivity
31. a) Frequency modulation
32. b) Amplitude modulation
33. b) Amplitude modulation
34. b) Frequency
35. d) PC modulation
36. c) Periodic
37. d) Building block
38. a) Applying a positive voltage to the p-side and negative voltage to the n-side
39. d) Applying a negative voltage to both the p-side and n-side
40. d) All of the above
