Power Electronics Basics
The term “power electronics” is given to the study of switching electronic circuits in the interest of controlling the flow of electrical energy, and serves as the technology behind a host of electricity-related processes. What do you know about it?
Questions and Answers
- 1.
A silicon controlled rectifier (SCR) is a
- A.
Unijunction device.
- B.
Device with 3 junctions.
- C.
Device with 4 junctions.
- D.
None of the above.
Correct Answer
B. Device with 3 junctions.Explanation
An SCR, or silicon controlled rectifier, is a device with 3 junctions. This means that it has 3 layers of semiconductor material, each forming a junction with the adjacent layer. The 3 junctions are formed by the P-N-P-N layers in the SCR structure. These junctions play a crucial role in the operation of the SCR, allowing it to function as a controlled rectifier, meaning it can control the flow of current in a circuit. Therefore, the correct answer is "device with 3 junctions."Rate this question:
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- 2.
Which of the following finds application in speed control of a dc motor?
- A.
FET
- B.
NPN transistor.
- C.
SCR.
- D.
None of the above.
Correct Answer
C. SCR.Explanation
The correct answer is SCR. SCR stands for Silicon Controlled Rectifier and it is a three-terminal semiconductor device that is commonly used for controlling the speed of a DC motor. It is a type of thyristor and can be used as a switch to control the flow of current to the motor. By varying the gate current, the firing angle of the SCR can be adjusted, which in turn controls the speed of the motor. FET and NPN transistor, on the other hand, are not typically used for speed control of DC motors.Rate this question:
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- 3.
A chopper can be used to step up a dc voltage.
- A.
True.
- B.
False.
Correct Answer
A. True.Explanation
A chopper is an electronic device that can be used to step up a DC voltage. It works by rapidly switching the input voltage on and off, and then using a filter to smooth out the resulting waveform. By adjusting the duty cycle of the switching signal, the output voltage can be increased or decreased. This makes a chopper a versatile tool for voltage conversion, including stepping up a DC voltage. Therefore, the statement "A chopper can be used to step up a DC voltage" is true.Rate this question:
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- 4.
A dc chopper converts directly from dc to dc.
- A.
True.
- B.
False.
Correct Answer
A. True.Explanation
A dc chopper is an electronic circuit that converts a fixed DC voltage to a variable DC voltage. It does this by chopping the input DC voltage into a series of pulses and then filtering and averaging the voltage to obtain the desired output. Therefore, it can be said that a dc chopper converts directly from dc to dc, making the statement true.Rate this question:
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- 5.
A triac is a
- A.
2 terminal switch.
- B.
2 terminal bilateral switch.
- C.
3 terminal unilateral switch.
- D.
3 terminal bidirectional switch.
Correct Answer
D. 3 terminal bidirectional switch.Explanation
A triac is a three-terminal bidirectional switch because it can conduct current in both directions when triggered. It is commonly used in AC applications to control the flow of current in both positive and negative half cycles of the alternating current. The three terminals of a triac are the main terminal 1 (MT1), main terminal 2 (MT2), and the gate terminal. By applying a control signal to the gate terminal, the triac can be turned on and off, allowing current to flow in either direction.Rate this question:
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