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Chapter 13 PHOTO-SENSITIVE BJT & LIGHT ACTIVATED SILICON CONTROL RECTIFIER (LASCR) MCQs

1. . In a phototransistor, base current is

(A) set by bias voltage


(B) not a factor


(C) inversely proportional to light


(D) directly proportional to light




2. . A large secondary current _________________ in n-p-n InGaAs phototransistor is achieved.

(A) Between base and collector


(B) Between base and emitter


(C) Between emitter and collector


(D) Plasma




3. . Which of the following is the difference between the n-p-n and conventional bipolar transistor?

(A) Electric property


(B) Magnetic property


(C) Unconnected base


(D) Emitter base efficiency




4. . The n-p-n hetero-junction phototransistor is grown using ______________

(A) Liquid-phase tranquilizers


(B) Liquid-phase epistaxis


(C) Solid substrate


(D) Hetero poleax




5. . What is the main benefit of the waveguide structure over conventional heterojunction phototransistor?

(A) High depletion region


(B) Depletion width


(C) Increased photocurrent, responsivity


(D) Low gain




6. . Solid State Relays (SSRs) have a

(A) coil and contact arrangement


(B) optocoupler


(C) scr


(D) none of the mentioned




7. . An LED and phototransistor is equivalent to a/an

(A) Thermocouple


(B) FET


(C) Optocoupler


(D) Regulator




8. . Optocoupler is otherwise known as

(A) Laser


(B) Photodiodes


(C) Photoconductive cell


(D) Optoisolator




9. . When the emitter junction is forward biased while the collector junction is reverse biased, the transistor is at ________ region.

(A) Cut-off


(B) Active


(C) Saturation


(D) Breakdown




10. . Which of the following has the highest input impedance

(A) FET


(B) BJT


(C) MOSFET


(D) Crystal diode




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