Thyristors And Tranducers MCQs
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A transducer’s function is to:
- A. transmit electrical energy
- B. convert energy
- C. produce mechanical energy
- D. prevent current flow
- Correct Answer: Option B
A TRIAC:
- A. can trigger only on positive gate voltages
- B. can trigger only on negative gate voltages
- C. cannot be triggered with gate voltages
- D. can be triggered by either a positive or a negative gate voltage
- Correct Answer: Option D
A UJT has:
- A. two base leads
- B. one emitter lead
- C. two emitter leads and one base lead
- D. one emitter lead and two base leads
- Correct Answer: Option D
An optically coupled isolator is a device containing _________ in a single package.
- A. a photodiode and an optotransmitter
- B. an LED and an SCR
- C. an anode and a cathode
- D. an IRED and a silicon phototransistor
- Correct Answer: Option D
Once a DIAC is conducting, the only way to turn it off is with:
- A. a positive gate voltage
- B. a negative gate voltage
- C. low-current dropout
- D. breakover
- Correct Answer: Option C
The DIAC is a:
- A. transistor
- B. unidirectional device
- C. three-layer device
- D. bidirectional device
- Correct Answer: Option D
The only way to close an SCR is with:
- A. a trigger input applied to the gate
- B. forward breakover voltage
- C. low-current dropout
- D. valley voltage
- Correct Answer: Option B
The PUT (programmable unijunction transistor) is actually a type of:
- A. UJT thyristor
- B. FET device
- C. TRIAC
- D. SCR
- Correct Answer: Option A
The smallest amount of current that the cathode-anode can have, and still sustain conduction of an SCR is called the:
- A. maximum forward current
- B. maximum forward gate current
- C. holding current
- D. reverse gate leakage current
- Correct Answer: Option D
The TRIAC is equivalent to ________________.
- A. a four-layer diode
- B. two DIACs in parallel
- C. a thyristor with a gate lead
- D. two SCRs in parallel
- Correct Answer: Option D
What causes the piezoelectric effect?
- A. heat or dissimilar metals
- B. pressure on a crystal
- C. water running on iron
- D. a magnetic field
- Correct Answer: Option B
What does a hall effect sensor sense?
- A. temperature
- B. moisture
- C. magnetic fields
- D. pressure
- Correct Answer: Option C
What is an SCR?
- A. a PNPN thyristor with 3 terminals
- B. a PNPN thyristor with 4 terminals
- C. a PNP thyristor with 3 terminals
- D. an NPN thyristor with 3 terminals
- Correct Answer: Option A
What type of application would use a photovoltaic cell?
- A. an automobile horn
- B. a TI 92 calculator
- C. a magnetic field detector
- D. a remote power source
- Correct Answer: Option D
What type of application would use an injection laser diode?
- A. a 10BASE-T Ethernet
- B. a liquid crystal display
- C. a fiber optic transmission line
- D. a good flashlight
- Correct Answer: Option C
When checking a good SCR or TRIAC with an ohmmeter it will:
- A. show high resistance in both directions
- B. show low resistance with positive on anode and negative on cathode, and high resistance when reversed
- C. show high resistance with negative on anode and positive on cathode, and low resistance when reversed
- D. show low resistance in both directions
- Correct Answer: Option A