MCQ
21. 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
22. Which causes the barrier layer in a PN Junction--
doping
barrier potential
recombination
ions
23. The output frequency of a full wave rectifier is-
Same as the input frequency
One-half of the input frequency
Double of the input frequency
Independent of the input frequency
24. An SCR has PN junctions.
Two
Four
Three
None of the above
25. The reverse current in a diode is of the order of—
KA
A
mA
uA
26. 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
27. In the normal operation of an SCR, anode is-- with respect to cathode.
at zero potential
negative
positive
none of the above
28. If the ac supply is 50Hz, what will be the ripple frequency out of the full wave rectifier?
50Hz
100Hz
60Hz
20Hz
29. An SCR has-semiconductor layers.
Two
Three
Four
None of the above
30. The battery connections required to forword bias a pn junction are-
+ve terminal to p and -ve terminal to n
-ve terminal to pand+ ve terminal to n
-ve terminal to p and-ve terminal to n
+ve terminal to pand+ ve terminal to n
31. An SCR is a --triggered device.
Voltage
current
Voltage as well as current
None of the above
32. The purpose of a gate is to---
deliver molten metal into the mold cavity.
act as a reservoir for the molten metal.
feed the molten metal to the casting in order to compensate for the shrinkage.
deliver molten metal from pouring basin to gate
33. If the temperature of the diode increases, then leakage current-
Remains same
Increases
Decreases
Becomes zero
34. In an SCR circuit, the generally --that of breakover voltage.
Equal to
Greater than
Less than
None of the above
35. 1 db corresponds to --- changes in voltage level.
12%
20%
80%
26%
36. 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
37. As the temperature of a transistor goes up the base-emitter resistance-
decreases
increases
remains the same
none
38. 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
39. A zener diode is destroyed if it-
is forward biased
is reverse biased
carriers more than rated current
none of the above
40. Noise factor of a ideal amplifier is---
0dB
5dB
0.5dB
10dB