Sensors and Actuators

Q-1 Which of the following statements is correct?

a) Actuators and transducers are both examples of sensors.
b) Sensors and actuators are both examples of transducers.
c) Sensors and transducers are both examples of actuators.

Correct Answer:

Sensors and actuators are both examples of transducers.

Q-2 What term describes the maximum expected error associated with a measurement or a sensor?

a) Precision.

b) Accuracy.

c) Resolution.

d) Range.

Correct Answer:

Accuracy.

Q-3 Which of the following forms of temperature sensor produces a large change in its resistance with temperature, but is very non-linear?

a) A platinum resistance thermometer.

b) A pn junction sensor.

c) A thermistor.

Correct Answer:

A thermistor.

Q-4 One of the most widely used forms of light sensor is the photodiode. Which of the following statements is correct?

a) A photodiode is an example of a photovoltaic sensor.

b) A photodiode can be used as either a photoconductive or a photovoltaic sensor.

c) A photodiode is an example of a photoconductive sensor.

Correct Answer:

A photodiode can be used as either a photoconductive or a photovoltaic sensor.

Q-5 The image below shows a strain gauge. With the device oriented as shown, what is the direction of sensitivity of the device?

 

a) Perpendicular to the plane of the device.

b) Vertical.

c) Horizontal.

Correct Answer:

Horizontal.

Q-6 What form of displacement sensors are shown here?

a) Opto-switches.

b) Potentiometers.

c) Inductive proximity sensors.

d) Absolute position encoders.

Correct Answer:

Inductive proximity sensors.

Q-7 Which of the following statements is correct?

a) A typical LED has an operating voltage of about 0.7 V.

b) The light output of an LED is approximately proportional to the current passing through it.

c) The light output of an LED is approximately proportional to the voltage across it.

Correct Answer:

The light output of an LED is approximately proportional to the current passing through it.

Q-8 Liquid crystal displays (LCDs) are widely used in a range of electronic systems. Which of the following describes the construction of such a display?

a) Two sheets of conducting material separated by a layer of insulating dielectric.

b) A pn junction formed using materials such as gallium arsenide or gallium phosphide.

c) Two sheets of polarized glass with a thin layer of oily material sandwiched between the

Correct Answer:

Two sheets of polarized glass with a thin layer of oily material sandwiched between them.

Q-9 In a stepper motor, how is the speed of rotation determined?

a) By the magnitude of the voltage applied.

b) By the current supplied to the motor.

c) By the load applied to the motor.

d) By the frequency of the waveforms used.

Correct Answer:

By the frequency of the waveforms used.

Q-10 A typical LED has an efficiency of about 75%.

a) True

b) False

Correct Answer:

False