Majorship LET Reviewer
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| LET Reviewer for TLE |
ELECTRONICS
1. It is an electronic device use to limit the flow of electric current.
A. capacitor
B. resistor
C. transistor
D. diode
2. It is an electronic device use to stow electric charge.
A. resistor
B. transistor
C. diode
D. capacitor
3. It is a solid state device use to amplify the small input signal to become large output signal.
A. resistor
B. transistor
C. diode
D. capacitor
4. It is the simplest solid state device which is use as rectifier.
A. transistor
B. diode
C. resistor
D. capacitor
5. It is a kind of electronic equipment use to measure resistance.
A. Voltmeter
B. Ohm meter
C. Ammeter
D. Wattmeter
6. It is a kind of diagram where all information its symbol and designation are emphasize.
A. Electricity
B. Schematic diagram
C. Wiring diagram
D. fish tailing diagram
7. It is a branch of physics which deals with the study of the behavior properties and control electrons in the circuit.
A. Electricity
B. Electronics
C. Radio Mechanics
D. Computer
8. It is a kind of circuit where there is a continuous flow of electric current.
A. Close circuit
B. Open circuit
C. Short circuit
D. Ground circuit
9. It is a process of removing unwanted copper from the PCB.
A. Soldering
B. Etching
C. Boring
D. Mounting
10. How much is the resistance of a 100 watts 120 volts light bulb?
A. 1.44 Ω
B. 14.4 Ω
C. 144 Ω
D. 1440 Ω
11. Commonly resistor is connected in a circuit to
A. drop voltage
B. drop reactance
C. increase voltage
D. increase reactance
12. If a given resistor has color coded value as brown, red, orange and gold, its nominal value is
A. 123 Ω ± 5%
B. 123 Ω ± 10%
C. 12,000 Ω ± 5%
D. 12,000 Ω ± 10%
13. When two resistors having different values are connected in parallel, their total resistance can be calculated as
A. RT = N/2
B. RT = R1 + R2
C. 1/RT = 1/R1 + 1/R2
D. none of the above
14. The total resistance of the resistors connected in series with values such as 1.2 k Ω and 500 Ω is
A. 1.7 k Ω
B. 1,700 Ω
C. 352.94 Ω
D. a and b
15. It is a property of circuit element which opposes any current change, and is measured in Henry, this is called
A. Capacitance
B. Inductance
C. Resistance
D. Conductance
16. The power transformer characterized with more number of turns at the primary than the secondary winding is a transformer known as
A. step-down
B. step-up
C. auto-transformer
D. isolating
17. Inductors L1 and L2 are in parallel with each other having the same values of 300mH. Their combined inductance is
A. 150mH
B. 600mH
C. 0
D. none of the above
18. If a power transformer has NP of 1800 turns, NS of 74 turns and EP of 220 V, how much is the ES?
A. 3 V
B. 6 V
C. 9 V
D. 12 V
19. Capacitor’s property which says how much charge can be stored units dielectric is referred to as
A. Resistance
B. Conductance
C. Inductance
D. Capacitance
20. A capacitor consists of two
A. conductors separated by an insulator
B. insulators separated by a conductor
C. conductors alone
D. insulators alone
21. To combine capacitances in series. It is computed simply by
A. 1/CT = 1/C1 + 1/C2
B. C = Q/V
C. CT = C1 + C2
D. None of the above
22. The unit of measure of electrical current is
A. Volt
B. Ampere
C. Ohm
D. Watt
23. When capacitors are connected in parallel, their capacitances can be calculated as
A. CT = C1 + C2
B. 1/CT = 1/C1 + 1/C2
C. C = Q/V
D. None of the above
24. A capacitance of 0.02 µF equals
A. 0.02 X 10¬¬-12 F
B. 0.02 X 10-6 F
C. 0.02 X 106 F
D. 200 X 10-12 F
25. When a semiconductor diode’s anode terminal is supplied with negative dc voltage and the cathode with positive dc voltage, the diode bias is
A. Forward
B. Reverse
C. No bias
D. More bias
26. When the arrow head on the electronic symbol of a semiconductor transistor is pointing inward, the type of transistor is
A. NPN
B. PNP
C. NPNP
D. PNPN
D. Larger than a no. 8 copper wire
27. If 12 volts are applied to a certain lamp whose filament has a resistance of 3 ohms, the current flow through the lamp filament will be
A. 4 amp
B. 36 amp
C. 8 amp
D. 12 amp
28. If a copper wire becomes heated because of an excessive amount of current flowing through it, the resistance of the wire
A. Decreases
B. Increases
C. Remains the same as when the wire is cold
D. Becomes zero
29. To measure the current flowing through a circuit, connect an
A. Ohm meter
B. Ammeter
C. Volt meter
D. Meter in series with the circuit
30. In the laboratory, to verify the current in a resistor, _______________.
A. an ammeter is connected in series with the resistor
B. a voltmeter is connected in series with the resistor
C. an ammeter is connected parallel to the resistor
D. a voltmeter is connected parallel to the resistor
31. Which statement is true?
a. An ammeter has negligible resistance.
b. A voltmeter has negligible resistance.
c. An ammeter measures voltage.
d. A voltmeter measures current.
32. Kirchhoff’s Current Law : nodes ; Kifchhoff’s Voltage Law : __________
a. junction
b. loops
c. meshes
d. b and c
33. Kirchhoff’s Laws are applicable to networks with series resistors.
a. Always true
b. Often time
c. Sometimes true
d. Never true
34. The conservation law that served as basis for Kirchhoff’s Current Law is _________.
a. conservation of charge
b. conservation of energy
c. conservation of mass
d. conservation of quantum numbers
35. Which statement is true about Kirchhoff’s Current Law?
a. The sum of the currents entering the node is equal to that leaving the same node.
b. The current in a conducting loop is the same for all resistors in the loop.
c. The numerical sum of the currents entering a node is zero.
d. The sum of the current over a loop is zero.
36. A capacitor and an inductor are electronic components that store electrical energy. How is an inductor different from a capacitor?
a. An inductor is an electromagnet
b. An inductor is made up of a coil of wire
c. An inductor may be made into a capacitor
d. An inductor stores energy in its magnetic field
37. Which of the following is NOT a function of a resistor in a circuit?
I. It limits the flow of current
II. It prevents short and overloading
III. It regulates the voltage of circuit elements
a. I only
b. II only
c. I and II
d. I, II and III
38. Which of the following describes a step up transformer?
Primary Coil
|
Secondary Coil
|
|||
| No. of Turns |
Voltage
|
No. of turns
|
Voltage
|
|
a.
|
200
|
10 V
|
50
|
100 V
|
b.
|
200
|
10 V
|
150
|
100 V
|
c.
|
200
|
10 V
|
200
|
100 V
|
d.
|
200
|
10 V
|
2000
|
100 V
|
39. How does a diode convert an AC signal to a DC signal?
a. By filtering the flow of current in the circuit
b. By allowing current to pass in one direction
c. By resisting the flow of current in the circuit
d. By regulating the flow of current in the circuit
40. Which of the following instrument is used to measure the amount of current flowing in an element in a circuit?
a. ammeter
b. ohmmeter
c. tester
d. voltmeter
41. A transformer has 250 turns in its secondary coil. The secondary voltage is 10 V. If the transformer is connected to a 220 V source, how many turns does the transformer have in its primary coil?
a. 5500
b. 2500
c. 500
d. 11
42. Which of the following semiconducting device serves as an amplifier in a circuit?
a. capacitors
b. diodes
c. integrated circuits
d. transistors
43. A step up transformer is used by power plants to transmit electrical power at a very high voltage over a large distance. Why is this so?
a. It is the cheapest way of transmitting electrical power.
b. Because large amount of power requires large amount of voltage for transmission.
c. Because high voltage transmission lines have almost zero resistance to the flow of current.
d. Because current is small in high voltage transmission lines preventing significant waste of electrical energy.
44. Which of the following semiconducting device is generally used as an indicator when an appliance is turned on or off?
a. Light emitting diodes
b. Photodiodes
c. Photoresistors
d. Small lamps
45. Compared to the primary coil, the number of turns in the secondary coil of a step up transformer is _____________.
a. less
b. more
c. the same
d. infinite
46. What does a changing magnetic field in a coil of wire produce?
a. An induced power
b. An induced voltage
c. An induced resistance
d. An induced coil polarity
47. Why does alternating current replace direct current for general use?
a. Alternating current has more power than direct current
b. Alternating voltages are convenient to transform
c. Generators always generate alternating current
d. Alternating current is safer than direct current
48. How does the audio signal of television networks transmitted?
a. By modulating the frequency of the wave
b. By modulating the amplitude of the wave
c By transforming it to an analog signal
d. By transforming it to a digital signal
49. A fuse or a circuit breaker is always connected in series with the appliance or the circuit that it intends to protect when short or overloading happens. Why is this so?
a. It is easier to connect a fuse in series than in parallel.
b. Short and overloading always happen in series circuits.
c. There is higher probability for overloading in parallel circuits.
d. There is only one path for current to flow in a series connection.
50. In the laboratory, to determine the voltage across a resistor, ______________.
a. an ammeter is connected in series with the resistor
b. a voltmeter is connected in series with the resistor
c. an ammeter is connected parallel to the resistor
d. a voltmeter is connected parallel to the resistor
51. Which statement is true?
a. An ammeter has negligible resistance
b. A voltmeter has negligible resistance
c. An ammeter measures voltage
d. A voltmeter measures current
52. Kirchhoff’s Current Law : conservation of charge ; Kirchhoff’s Voltage Law : __________
a. conservation of mass
b. conservation of energy
c. conservation of quantum numbers
d. b and c
53. Kirchhoff’s Laws is applicable to networks containing any electrical elements.
a. Always true
b. Often time
c. Sometimes true
d. Never true
54. Kirchhoff’s Voltage Law is applicable to networks containing ___________.
a. capacitors
b. inductors
c. potential and current sources
d. resistors
55. Which statement is NOT true about Kirchhoff’s Laws?
a. The numerical sum of the voltage rise and that of the potential drop in a conducting loop are equal.
b. The sum of the voltage rise and the voltage drop in a conducting loop is zero.
c. The voltage across any resistor in a loop is always a voltage drop.
d. The voltage across a voltage source is sometimes a voltage drop.
56. Compared to the primary coil, the number of turns in the secondary coil of a step down transformer is _____________.
a. less
b. more
c. the same
d. infinite
57. How does the video signal of television networks transmitted?
a. By modulating the frequency of the wave
b. By modulating the amplitude of the wave
c By transforming it to an analog signal
d. By transforming it to a digital signal
58. Which of the following describes a step down transformer?
Primary Coil
|
Secondary Coil
|
|||
No. of turns
|
Voltage
|
No. of turns
|
Voltage
|
|
a.
|
50
|
100 V
|
200
|
10 V
|
b.
|
150
|
100 V
|
200
|
10 V
|
c.
|
200
|
100 V
|
200
|
10 V
|
d.
|
2000
|
100 V
|
200
|
10 V
|
59. Which of the following instrument is used to measure the potential difference across an element in a circuit?
a. Ammeter
b. Ohmmeter
c. Tester
d. Voltmeter
60. The amount of energy consumed by an appliance per unit time is indicated as the appliance’s
a. current
b. power
c. resistance
d. voltage
61. Which of the following can be a function of a transistor in a circuit?
a. Amplifies current or electric signals
b. Limits the flow of current
c. Stores electrical energy
d. Regulates voltage
62. A battery has a voltage of 12 V. What does this mean?
a. Both terminals of the battery have a 12 V electric potential.
b. Both terminals of the battery have the same electric potential.
c. One of the terminals of the battery is 12 V and the other is 0 V.
d. One of the terminals of the battery is 12 V higher in electric potential than the other.
63. Which of the following device best demonstrates the concept that magnetism exerts a force on a moving charge?
a. Diode
b. Generator
c. Motor
d. Transformer
64. Which of the following can cause electric shock?
a. Current and power
b. Current and voltage
c. Voltage and power
d. Voltage and resistance
65. Which of the following can serve as a source of radio waves transmitted by telecommunications systems?
a. Electromagnetic waves
b. Nuclear reactions
c. Electric circuits
d. The sun
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