1.
How many semiconductor layers does an SCR have?
2.
Which one of the following is used as the main switching element in a switched mode power supply operating in 20 kHz to 100 kHz range?
3.
A thyristors are not made using germanium, because
4.
The typical turn-off time of an SCR is about
5.
Which of the following is a four-layer diode with an anode gate and a cathode gate?
6.
To turn off the SCR, which of the following is done?
7.
Commutation overlap in the phase-controlled ac to dc converter is due to
8.
Which terminal does not belong to the SCR?
10.
Which one of the following is the most suitable device for a dc to dc converter?
11.
The use of multiphase rectifier in place of one phase rectifier results in
12.
Once an SCR is turned on, it remains so until the anode current goes below
13.
Which of the following is a common application of UJT?
14.
Consider the following statements:
A four-layer PNPN device having two gate leads can be turned on by applying a
1. positive current pulse to the cathode gate
2. positive current pulse to the anode gate
3. negative current pulse to the anode gate
4. negative current pulse to tha cathode gate
which of these statement is /are correct
15.
A boost-regulator has an input voltage of 5V and the average output voltage of 15 V. The duty cycle is
16.
What is the sensing element of acceleration transducer?
18.
The minimum gate current which can turn on SCR is called:
19.
Most SCRs can be turned-off by voltage reversal during negative half cycle of the ac supply for
20.
In a single-phase semiconverter with resistive load and for a firing angle α , each SCR conduction and freewheeling action takes place
21.
As compared to power MOSFET, a BJT has
22.
A freewheeling diode is connected across R-L load, because
23.
What is the control element in an SCR?
24.
A single-phase half wave rectifier circuit has a freewheeling diode. The freewheeling diode will conduct only if
25.
An SCR is considered to be a semicontrolled device because
26.
Which of the following is the normal way to turn on a diac?
27.
When fed from a fully controlled rectifier, a dc motor, driving an active load can operate in
28.
The latching current is _________ than the holding current
29.
Current in SCR to turn on transient can be reduced by
30.
The three terminals of a triac are
31.
In a feedback series regulator circuit, the output voltage is regulated by controlling the
32.
When the emitter terminal of a UJT is open, the resistance between the base-terminals is generally
33.
R-C snubber is used in parallel with the thyristor to
34.
Which equation defines the intrinsic stand off ratio (y) of UJTs?
35.
Which of the following configurations is used for both motoring and regenerative braking?
36.
Which is equivalent to a zener or avalanche region of the fundamental two-layer semiconductor diode?
37.
How many semiconductor layers does a triac have?
38.
For an SCR, dv/dt protection is achieved through the use of
39.
Switching regulators are also called
40.
Which device does not have a gate terminal?
41.
Which of the following is the normal way to turn on an SCR?
42.
1. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device.
43.
The shunt type regulator is suitable for which of the following?
44.
The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of in the quotation.
45.
In the SCR structure the gate terminal is located
46.
What is the ratio of two exponential functions of time called?
47.
Natural commutation can be used in:
48.
An emitter follower regulator has the following disadvantage :
49.
Which one of the following statements is correct? In the case of load regulation
50.
An SCR is in conducting state, a reverse voltage is applied between anode and cathode, but it fails to turn off. what could be the reason?
