1. .1 A UJT has
(A) Two PN junctions
(B) One PN junction
(C) Three PN junctions
(D) None of the above
2. .2 In a UJT, the p-type emitter is
(A) Lightly doped
(B) None of the above
(C) Moderately doped
(D) Heavily doped
3. .3 Internally UJT acts as?
(A) Inductance divider
(B) Capacitance divider
(C) Voltage divider
(D) Current divider
4. .4 When the emitter terminal of a UJT is open; the resistance between the base terminals is generally
(A) High
(B) Low
(C) Extremely low
(D) None of the above
5. .5 When a UJT is turned ON, the resistance between emitter terminal and lower base terminal
(A) Is decreased
(B) Remains the same
(C) Is increased
(D) None of the above
6. .6 To turn on UJT, the forward bias on the emitter diode should be the peak point voltage.
(A) Less than
(B) More than
(C) Equal to
(D) None of the above
7. .7 A UJT is sometimes called
(A) Low resistance diode
(B) High resistance diode
(C) Single-base diode
(D) Double-based diode
8. .8 Between the peak point and the valley point of UJT emitter characteristics we have
(A) Saturation region
(B) Cut-off region
(C) Negative resistance region
(D) None of the above region
9. .9 Which of the following is not a characteristic of UJT?
(A) Intrinsic standoff ratio
(B) Negative resistance
(C) Peak-point voltage
(D) Bilateral conduction
10. .10 The UJT may be used as
(A) A saw tooth generator
(B) An amplifier
(C) A rectifier
(D) None of these
11. .11 The device that exhibits negative resistance region is
(A) Diac
(B) Triac
(C) UJT
(D) Transistor
12. .12 In a phototransistor, base current is
(A) Directly proportional to light
(B) Set by a bias voltage
(C) Inversely proportional to light
(D) Not a factor
13. .13 Phototransistors are used in
(A) Optocouplers
(B) All of these
(C) Optical fiber
(D) Relay control circuits
14. .14 The phototransistor effectively converts variations in light energy to
(A) Digital signals
(B) An electrical signal
(C) Chemical energy
(D) Mechanical energy
15. .15 LASCR, when activated by a sufficient amount of light, conducts current
(A) In both directions
(B) In one direction
(C) In either one or both directions
(D) Do not conduct
16. .16 LASCR conducts by applying light of specific
(A) Intensity
(B) Frequency
(C) Time
(D) None of these
17. .17 The key advantage of an optocoupler between the input and output circuits is the electrical
(A) Connection
(B) None of these
(C) Both a & b
(D) Isolation
18. .18 Which of the following is not a type of an Optocoupler
(A) UJT
(B) Photo-darlington
(C) Photo-SCR
(D) Photo-transistor
19. .19 An electronic component that interconnects two separate electrical circuits by means of a light sensitive optical interface
(A) Triac
(B) Optocoupler
(C) SCR
(D) Diac
20. .20 The optocouplers works well on high-voltage signals.
(A) AC only
(B) Either AC or DC
(C) DC only
(D) None of the above