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1) Which of following is normally ON device? a. SIT b. BJT c. TRIAC d. IGBT
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2) Typical range of thyristor turn OFF time is______________? a. 3 – 10 µs b. 3 – 50 µs c. 3 – 100 µs d. 3 – 500 µs
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3) Power transistor are type of___________? a. B.JTs b. MOSFETs c. IGBTs d. All of above
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4) During gate recovery time_____________? a. charge carriers of J2 junction recombined b. charge carriers of J2 junction is swept out c. charge carrier of J1 junction removed d. charge carriers of J3 junction is removed
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5) During reverse recovery time__________________? a. charge carrier of junction J2 recombined b. charge carrier of junction J1 is swept out c. charge carrier of junction J3 is swept out d. both B and C
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6) Which of the following is true about SIT? a. SIT is a high power, high frequency device b. SIT is a high power, low frequency device c. SIT is a high power, high voltage device d. SIT is a low power, high frequency device
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7) During which time maximum conduction spreading take place in the thyristor during turn ON? a. Delay time b. Spread time c. Rise time d. Same for every case
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8) A GTO can be turned on by applying___________? a. Positive gate signal b. Positive drain signal c. Positive source signal d. None of these
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9) SITH is also known as___________? a. Filled controlled diode b. Filled controlled rectifier c. Silicon controlled rectifier d. None of these
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10) The typical time of rising time lies between______________? a. 10 – 20 µs b. 40 – 60 µs c. 1 – 4 µs d. 90 – 100 µs
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11) The reverse recovery time of diode is trr = 3 μs and the rate off all of the diode current is di/dt = 30 A/μs. The storage charge current QRR is___________? a. 130 μs b. 135 μs c. 140 μs d. 145 μs
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12) Maximum power loss occurs during_________________? a. delay time b. rise time c. spread time d. all
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13) Spread time is defined as the interval during which_____________? a. anode voltage drops from 10 % of its initial value to zero b. anode current rises from 90 % to its final value c. both (A) and (B) d. anode current rises from 10 % to 90 % of its final value
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14) The turn-on time of an SCR with inductive load is 20 µs. The puls train frequency is 2.5 KHz with a mark/space ratio of 1/10, then SCR will___________? a. Turn on b. Not turn on c. Turn on if inductance is removed d. Turn on if pulse frequency us increased to two times
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15) A power MOSFET has three terminals called___________? a. Collector, emitter and gate b. Drain, source and gate c. Drain, source and base d. Collector, emitter and base
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16) Rise time is defined by the interval when____________? a. gate current rises from 90 % to 100 % of it final value b. anode voltage drops from 90 % to 10 % of its initial value c. anode current rises 10 % to 90 % of its final value d. both B and C
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17) A modern power semiconductor device that combines the characteristic of BJT and MOSFET is_____________? a. IGBT b. FCT c. MCT d. GTO
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18) Delay time is defined by the interval when_______________? a. gate current increases from 90 % to 100 % of its final value b. anode current reaches 10 % from forward leakage current c. anode voltage drops from 100 % to 90 % of its actual value d. all of these
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19) Which one is most suitable power device for high frequency (>100 KHz) switching application? a. BJT b. Power MOSFET c. Schottky diode d. Microwave transistor
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20) Snubber circuit is used with SCR_________________? a. in series b. in parallel c. either series or parallel d. anti parallel
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