Industrial Electronics

31. How many semiconductor layers does an SCR have?

1. Four
2. Two
3. Three
4. Five

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32. If a body is considered as a conducting sphere of 0.5m radius its capacitance to infinity is

1. 55 pF
2. 55 nF
3. 55 μF
4. 55 F

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33. In diagnostic radiology and for superficial therapy purposes, the energy spectrum of radiation varies from about

1. 1 to 10 KeV
2. 10 to 100 KeV
3. 100 to 10000 KeV
4. 10000 to 100000 KeV

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34. In therapeutic radiology and in nuclear medicine, the energies of interest range from about

1. 10 to 100 KeV
2. 100 to 10000 KeV
3. 10000 to 10000 KeV
4. 1 to 10 KeV

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35. Power electronics deals with the control of ac power at what frequencies essentially?

1. 20 KHz
2. 1000 KHz
3. Frequencies less than 10 Hz
4. 60 Hz frequency

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36. PUT stands for

1. Programmable Unijunction Transistor
2. Programmable Universal Transistor
3. Pulse Unijunction Transistor
4. Pulse Universal Transistor

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37. SCR is a rectifier constructed of silicon material. Silicon is chosen because

1. it is the most abundant material
2. of its strength and ruggedness
3. it is much cheaper than any other material
4. of its high temperature and power capabilities

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38. The gate of an SCR is _________ with respect to its cathode.

1. positive
2. at zero potential
3. negative
4. at infinite potential

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39. The p-type emitter of a UJT is _________ doped.

1. lightly
2. moderately
3. heavily
4. not

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40. The SCR can exercise control over _________ of ac supply.

1. positive or negative half-cycle
2. both positive and negative half-cycles
3. only positive half-cycle
4. only negative half-cycle

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