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Electronics Engineering Objective Questions { Power Semiconductor Devices and Their Applications }

141.  In single-phase full-wave controlled bridge rectifier, maximum output voltages is obtained at ____ conduction angle and ____minimum at conduction angle?
A. 0?, 180?
B. 180?, 00
C. 0?, 0?
D. 180?, 180?
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142. A single-phase AC regulator with an inductance load has the following details Source voltage, 230 V, at a frequency of 50 Hz and coL = 5 ohms. The control range of the firing angle is
A. 0 < a < TC
B. ? < a < 71 2 ?
C. 0 a < ?2
D. it < a < 2
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143. In a SCR,
A. the holding current is less or greater than latching current
B. the holding current is five times the latching current
C. the two currents are equal
D. the latching current is about 3 times the holding current
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144. A thyristor and transistor as a switch are compared. The true ones are
A. Thyristor requires turn off circuit while transistor does not.
B. The voltage drop of thyristor is less than transistor.
C. ?Thyristor draws continuously base current.
D. none of the above
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145.  A thyristor is in the forward blocking state. Then
A. all the 3 junctions are reverse biased
B. the anode and cathode junctions are forward baised but the gate junction is reverse biased
C. the anode junction is forward biased but the other two, cathode and gate junctions are reverse biased
D. the anode and gate junctions are forward biased but the cathode junction is reverse biased.
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146. The turn-off tune of a lhyristor is 30 sec at 50?C. It's run off time at 100? is
A. same
B. l5 .t sec
C. 60p sec
D. 100p sec
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147. A continuous signal and a pulse are applied to the gate of thyristor. The thyristor will turn-on faster with
A. pulse
B. continuous signal
C. both same time
D. pulse but with minimum duration
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