239. If firing angle in an SCR circuit is increased, the output
A. remains the same
B. is increased
C. is decreased
D. none of the above
240. If gate current is increased, then anode-cathode voltage at which SCR closes
A. is decreased
B. is increased
C. remains the same
D. none of the above
241. When SCR is OFF, the current in the circuit is
A. exactly zero
B. small leakage current
C. large leakage current
D. none of the above
242. An SCR can exercise control over of a.c. supply.
A. positive half-cycles only
B. negative half-cycles only
C. both positive and negative half-cycles
D. positive or negative half-cycles
243. We can control a.c. power in a load by connecting
A. two SCRs in series
B. two SCRs in parallel
C. two SCRs in parallel opposition
D. none of the above
244. When SCR starts conducting, then loses all control.
A. gate
B. cathode
C. anode
D. none of the above
245. The values of voltage (VD) across a tunnel-diode corresponding to peak and valley currents are VP and Vv respectively. The range of tunnel-diode voltage VD kr which the slope of its I-VD characteristics is negative would be
A. VD < 0
B. N/D
D. VD Vv
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