MCQ
2521. If the ac supply is 50Hz, what will be the ripple frequency out of the full wave rectifier?
50Hz
100Hz
60Hz
20Hz
2522. AC power in a load can be controlled by connecting-
Two SCRs in series
Two SCRs in parallel
Two SCRs in parallel opposition
None of the above
2523. In an SCR circuit, the generally --that of breakover voltage.
Equal to
Greater than
Less than
None of the above
2524. When SCR starts conducting, which loses all control?
Cathode
Anode
Gate
None of the above
2525. Approximately how many milliamperes of current flow through circuit with a 40V source and 6.8 ΚΩ of resistance?
27.2 mA
5.9 mA
59 mA
590 mA
2526. What is the approximate resistance setting of a rheostat in which 650 mA of current flows with a 150V source?
9.7 Ω
97 Ω
23 Ω
230 Ω
2527. An SCR has PN junctions.
Two
Four
Three
None of the above
2528. An SCR is turned off when-
Anode current is reduced to zero.
Gate voltage is reduced to zero.
Gate is reverse biased.
None of the above.
2529. An SCR has three terminals viz-
anode, cathode, grid
cathode, anode, gate
anode, cathode, drain
none of the above
2530. An SCR behaves as a—switch.
Unidirectional
Mechanical
Bidirectional
None
2531. If firing angle is increased, then the output of an SCR-
Remains the same
Is increased
Is decreased
None of the above
2532. If gate current is increased, then anode-cathode voltage at which SCR turns ON-
is decreased
remains the same
is increased
none of the above
2533. An SCR is a --triggered device.
Voltage
current
Voltage as well as current
None of the above
2534. The parallel combination of a 470 Ω resistor and a 680 Ω resistor is in series resistors with the parallel combination of four 2k Ω The total resistance is-
1.650 Ω
1.0782 Ω
77.8Ω
778 Ω
2535. An SCR has-semiconductor layers.
Two
Three
Four
None of the above
2536. An SCR is a solid state equivalent of-
Triode
Gas-filled triode
Pentode
Tetrod
2537. If the temperature of the diode increases, then leakage current-
Remains same
Increases
Decreases
Becomes zero
2538. A voltage divider consists of two 100k resistors and a 12V source. What will the output voltage be if a load resistor of 1 MQ is connected to the output?
0.57V
12V
5.7 V
6 V
2539. In an SCR circuit, the angle of conduction can be changed by-
Changing anode voltage.
Changing gate voltage.
Reverse biasing the gate.
None of the above
2540. An SCR is made of silicon and not germanium because silicon-
is inexpensive
is mechanically strong
has small leakage current
is tetravalent