Thyristors and Tranducers MCQs

Question 1

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

Accepted Answer

show high resistance in both directions

Answer

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

Answer

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

Answer

show low resistance in both directions

Question 2

What does a hall effect sensor sense?

Accepted Answer

magnetic fields

Answer

temperature

Answer

moisture

Answer

pressure

Question 3

What causes the piezoelectric effect?

Accepted Answer

pressure on a crystal

Answer

heat or dissimilar metals

Answer

water running on iron

Answer

a magnetic field

Question 4

A UJT has:

Accepted Answer

one emitter lead and two base leads

Answer

two base leads

Answer

one emitter lead

Answer

two emitter leads and one base lead

Question 5

The only way to close an SCR is with:

Accepted Answer

forward breakover voltage

Answer

a trigger input applied to the gate

Answer

low-current dropout

Answer

valley voltage

Question 6

What is an SCR?

Accepted Answer

a PNPN thyristor with 3 terminals

Answer

a PNPN thyristor with 4 terminals

Answer

a PNP thyristor with 3 terminals

Answer

an NPN thyristor with 3 terminals

Question 7

What type of application would use a photovoltaic cell?

Accepted Answer

a remote power source

Answer

an automobile horn

Answer

a TI 92 calculator

Answer

a magnetic field detector

Question 8

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

Accepted Answer

reverse gate leakage current

Answer

maximum forward current

Answer

maximum forward gate current

Answer

holding current

Question 9

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

Accepted Answer

low-current dropout

Answer

a positive gate voltage

Answer

a negative gate voltage

Answer

breakover