Question 1

RTDs are constructed of metal and have a ____.

Accepted Answer

RTDs (Resistance Temperature Detectors) are constructed of metal and have a positive temperature coefficient, meaning their resistance increases with an increase in temperature.

Question 2

____ are constructed of metallic oxides and exhibit a negative temperature coefficient.

Accepted Answer

Thermistors are made of metallic oxides and are known for their negative temperature coefficient, meaning their resistance decreases as temperature increases.

Question 3

During normal operation, the noninverting input of the amplifier is connected to a ____.

Accepted Answer

The noninverting input of an amplifier is typically connected to a reference voltage for biasing purposes, and a Zener diode is commonly used for this because it can provide a stable reference voltage. Gunn diodes, square diodes, and dipole diodes are not standard components or terms associated with this application.

Question 4

As long as the noninverting input is more negative than the inverting input, the output of the amplifier  will be high.

Accepted Answer

For a typical operational amplifier, when the noninverting (+) input is more positive than the inverting (-) input, the output will be high. If the noninverting input is more negative, the output will typically be low.

Question 5

If the zener diode is replaced with a ____, the reference voltage can be set to any value desired.

Accepted Answer

A voltage divider allows for the adjustment of the output voltage to any desired value within its range, making it suitable for setting a specific reference voltage when replacing a zener diode.

Question 6

When the 741 op amp is used as an inverted amplifier, the zener diode produces a constant positive  voltage at the noninverting input of an amplifier and is used as a reference.

Accepted Answer

In an inverted amplifier configuration using a 741 op amp, a Zener diode can indeed be used to provide a constant positive voltage at the noninverting input. This setup establishes a stable reference voltage, ensuring that the amplifier operates within a specific range and improves the accuracy of the amplification process.

Question 7

Schematic diagrams, in a universally accepted practice, point the arrow through a resistor toward the  top of the circle to indicate the use of an RTD, and toward the bottom of the circle to indicate the use  of a thermistor.

Accepted Answer

Schematic diagrams do not universally use the direction of an arrow through a resistor symbol to differentiate between an RTD (Resistance Temperature Detector) and a thermistor. Instead, they often use different symbols or annotations to distinguish between the two types of temperature sensors.

Question 8

____ are devices that exhibit a change of resistance with a change of temperature.

Accepted Answer

Temperature dependent resistors, also known as thermistors, change their resistance with changes in temperature. This property makes them useful in temperature sensing and control applications.

Question 9

The advantage of the RTD is that it has a low temperature coefficient.

Accepted Answer

RTDs (Resistance Temperature Detectors) are valued for their high accuracy and repeatability over a wide temperature range, primarily due to their high temperature coefficient, which allows for precise temperature measurements.

Question 10

The operational amplifier is often used as a level detector or comparator.

Accepted Answer

The operational amplifier can be configured as a comparator to compare two voltage inputs and provide an output that indicates which input is larger. It can also be used as a level detector to detect when a signal reaches a certain threshold voltage.

Quiz 39: The 741 Op Amp Level Detector