Reference no: EM131084175
Questions 1 to 20: Select the best answer to each question. Note that a question and its answers may be split across a page break, so be sure that yon have seen the entire question and all the answers before choosing an answer.
1. A VDR converts changes in voltage to changes in
A. resistance.
B. current.
C. power.
D. pressure.
2. Which of the following would most likely use a Hall-Effect device?
A. An electrostatic voltmeter
B. A time-delay relay
C. A clamp-type ammeter
D. A thermistor bridge
3. Which of the following statements regarding a thermistor is true?
A. It is an example of a nonlinear resistor.
B. It is not a transducer.
C. It must have a negative temperature coefficient.
D. It can change resistance in response to changes in temperature.
4. A carbon button in a carbon microphone works like
A. a variable capacitor.
B. a variable resistor.
C. a variable inductor.
D. an amplifying transistor.
5. Which of the following waveforms is forbidden in electronic communications by international law?
A. A high-frequency sawtooth modulation
B. A VHF radio wave modulation
C. A damped wave
D. A low-frequency audio wave
6. Which of the following are used to run low-power circuits, recharge nicad batteries, and trigger relays?
A. Metal-oxide varistors
B. Shockley diodes
C. Piezoresistive pressure sensors
D. Photovoltaic cells
7. Load cells function using
A. strain gages.
B. resistors.
C. hydraulic presses.
D. Bolometers.
8. The rms value of the current or voltage for a sine wave is equal to
A. 0.637 times the maximum value.
B. 1.111 times the average value.
C. 1.111 times the peak-to-peak value.
D. 0.707 times the average value.
9. Which of the following devices would most likely use a piezoelectric transducer?
A. A carbon microphone
B. A crystal microphone
C. A ribbon microphone
D. A condenser microphone
10. Which of the following would likely be found in a meter designed to measure rms current?
A. A thermocouple
B. A Hall-effect device
C. A piezoelectric device
D. A magnetostrictive device
11. An ohmmeter functions to measure a resistor's resistance by sending a small amount of through that resistor.
A. voltage
B. silicon dioxide
C. current
D. stress
12. With a photodiode, the reverse current in response to an increase in light intensity.
A. decreases
B. stabilizes
C. increases
D. vanishes
13. Which of the following is an electromagnetic transducer?
A. A speaker
B. A piezoelectric crystal
C. A thermocouple
D. A thermistor
14. A resistor can be used as a
A. strain gage.
B. laser.
C. pressure transducer.
D. noise generator.
15. "When a magnetic field passes at an angle of ninety degrees through a current-carrying conductor, a voltage forms at a right angle to the current." This is a description of
A. Hooke's Law.
B. Kirchoffs Law.
C. The Hall Effect.
D. The Thompson Effect.
16. The random motion of free electrons throughout a resistor at any temperature above absolute zero is called current.
A. thermoelectric
B. extrinsic
C. reflex
D. intrinsic
17. A switch is used to turn on current to a large inductor. Which of the following would be connected across the switch to prevent arcing from causing contact damage?
A. A Hall device
B. An NTC thermistor
C. A resistor
D. A PTC thermistor
18. The force needed to cause a piece of wood to bend is called
A. stress.
B. strain.
C. the force field.
D. the reflex field.
19. Varistors are often used in circuits as protection devices because
A. most circuits aren't subjected to changes in temperature.
B. most circuits need only a small amount of protection.
C. varistors can react very quickly to voltage overloads.
D. varistors can be purchased and installed quickly.
20. Which of the following devices is sometimes used to increase the life span of a light bulb?
A. A Piezoelectric device
B. A series inductor
C. A thermistor
D. A Hall device