Thyristors And Tranducers(Engineering > Electronics And Communication Engineering ) Questions and answers for exam Preparation

Question 1. What does a hall effect sensor sense?

temperature
moisture
magnetic fields
pressure

Explanation:-

Answer: Option C. -> magnetic fields

Question 2. A UJT has:

two base leads
one emitter lead
two emitter leads and one base lead
one emitter lead and two base leads

Explanation:-

Answer: Option D. -> one emitter lead and two base leads

Question 3. A TRIAC:

can trigger only on positive gate voltages
can trigger only on negative gate voltages
cannot be triggered with gate voltages
can be triggered by either a positive or a negative gate voltage

Explanation:-

Answer: Option D. -> can be triggered by either a positive or a negative gate voltage

Question 4. When checking a good SCR or TRIAC with an ohmmeter it will:

show high resistance in both directions
show low resistance with positive on anode and negative on cathode, and high resistance when reversed
show high resistance with negative on anode and positive on cathode, and low resistance when reversed
show low resistance in both directions

Explanation:-

Answer: Option A. -> show high resistance in both directions

Question 5. What causes the piezoelectric effect?

heat or dissimilar metals
pressure on a crystal
water running on iron
a magnetic field

Explanation:-

Answer: Option B. -> pressure on a crystal

Question 6. The only way to close an SCR is with:

a trigger input applied to the gate
forward breakover voltage
low-current dropout
valley voltage

Explanation:-

Answer: Option B. -> forward breakover voltage

Question 7. What is an SCR?

a PNPN thyristor with 3 terminals
a PNPN thyristor with 4 terminals
a PNP thyristor with 3 terminals
an NPN thyristor with 3 terminals

Explanation:-

Answer: Option A. -> a PNPN thyristor with 3 terminals

Question 8. The smallest amount of current that the cathode-anode can have, and still sustain conduction of an SCR is called the:

maximum forward current
maximum forward gate current
holding current
reverse gate leakage current

Explanation:-

Answer: Option D. -> reverse gate leakage current

Question 9. What type of application would use a photovoltaic cell?

an automobile horn
a TI 92 calculator
a magnetic field detector
a remote power source

Explanation:-

Answer: Option D. -> a remote power source

Question 10. . Once a DIAC is conducting, the only way to turn it off is with:

a positive gate voltage
a negative gate voltage
low-current dropout
breakover

Explanation:-

Answer: Option C. -> low-current dropout