127. A SCR has __ PN junctions.
A. two
B. four
C. three
D. one

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128. If gate current is increased, the anode-cathode voltage at which SCR closes is
A. increased
B. decreased
C. maximum
D. least

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129. A conducting SCR can be opened by reducing ... to zero.
A. supply voltage
B. grid voltage
C. grid current
D. anode current

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130. With gate open, a SCR can be turned-on by making supply voltage
A. minimum
B. reverse
C. equal to cathode voltage
D. equal to break-over voltage

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131. If firing angle in a SCR rectifier is increased, output is
A. increased
B. maximum
C. decreased
D. unaffected

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132. A SCR is a ___ switch.
A. two directional
B. unidirectional
C. three directional
D. four directional

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133. If the chopper switching frequency is 200 Hz and ton time is 2 ins, the duty cycle is
A.0.4
B.0.8
C.0.6
D. none of these

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