Daily review: Temperature Sensor | Impedance…

Q: What is the primary characteristic of an NTC thermistor as temperature increases?

Resistance decreases non-linearly — NTC (Negative Temperature Coefficient) thermistors exhibit a non-linear decrease in resistance as temperature rises.

Q: In a simple voltage divider with resistors R1 and R2, where the output is taken across R2, what is the formula for Vout?

Vin * (R2 / (R1 + R2)) — The voltage divider rule states Vout = Vin * [R_load / (R_total)], where R_load is the resistor across which voltage is measured.

Q: What is the complex impedance Z of a series RC circuit at a given frequency ??

R - j/(?C) — Impedance of a capacitor is 1/(j?C), which equals -j/(?C). Adding the series resistor R gives R - j/(?C).

Q: If a 10k? resistor (R1) is in series with a 10k? thermistor (R2) connected to a 5V source, what is Vout across the thermistor?

2.5V — With equal resistors, the voltage splits equally: 5V / 2 = 2.5V.

Q: What happens to the phase angle of a circuit dominated by inductive impedance as frequency increases?

Phase angle becomes more positive (towards 90 degrees) — Inductive reactance X_L = ?L increases with frequency, making the circuit more inductive, pushing phase toward +90°.

Q: Why is a voltage divider circuit often used with resistive temperature sensors (RTDs or Thermistors)?

To convert a resistance change into a measurable voltage change — Microcontrollers measure voltage; the divider converts the sensor's varying resistance into a signal the ADC can interpret.

Q: What is the magnitude of the impedance |Z| of an RL circuit with R=3? and X_L=4??

5? — Magnitude |Z| = sqrt(R² + X_L²) = sqrt(3² + 4²) = sqrt(9 + 16) = 5?.

Q: In a voltage divider circuit, what is the effect of having a very high load impedance connected to Vout?

It has negligible effect on the Vout calculated by the divider rule — An ideal voltage divider assumes no current is drawn by the load; a very high load impedance approximates this condition.

Q: What does the 'j' operator represent in complex impedance analysis?

The imaginary unit, representing a 90-degree phase shift — The imaginary unit j (or i) denotes the 90-degree phase relationship between resistive and reactive components.

Q: Which of the following is true for an RTD (Resistance Temperature Detector) compared to a thermistor?

RTDs are usually more linear — RTDs (typically platinum) have a much more linear relationship between temperature and resistance compared to thermistors.

Question 1 of 10

What is the primary characteristic of an NTC thermistor as temperature increases?

NTC (Negative Temperature Coefficient) thermistors exhibit a non-linear decrease in resistance as temperature rises.

Question 2 of 10

In a simple voltage divider with resistors R1 and R2, where the output is taken across R2, what is the formula for Vout?

The voltage divider rule states Vout = Vin * [R_load / (R_total)], where R_load is the resistor across which voltage is measured.

Question 3 of 10

What is the complex impedance Z of a series RC circuit at a given frequency ??

Impedance of a capacitor is 1/(j?C), which equals -j/(?C). Adding the series resistor R gives R - j/(?C).

Question 4 of 10

If a 10k? resistor (R1) is in series with a 10k? thermistor (R2) connected to a 5V source, what is Vout across the thermistor?

With equal resistors, the voltage splits equally: 5V / 2 = 2.5V.

Question 5 of 10

What happens to the phase angle of a circuit dominated by inductive impedance as frequency increases?

Inductive reactance X_L = ?L increases with frequency, making the circuit more inductive, pushing phase toward +90°.

Question 6 of 10

Why is a voltage divider circuit often used with resistive temperature sensors (RTDs or Thermistors)?

Microcontrollers measure voltage; the divider converts the sensor's varying resistance into a signal the ADC can interpret.

Question 7 of 10

What is the magnitude of the impedance |Z| of an RL circuit with R=3? and X_L=4??

Magnitude |Z| = sqrt(R² + X_L²) = sqrt(3² + 4²) = sqrt(9 + 16) = 5?.

Question 8 of 10

In a voltage divider circuit, what is the effect of having a very high load impedance connected to Vout?

An ideal voltage divider assumes no current is drawn by the load; a very high load impedance approximates this condition.

Question 9 of 10

What does the 'j' operator represent in complex impedance analysis?

The imaginary unit j (or i) denotes the 90-degree phase relationship between resistive and reactive components.

Question 10 of 10

Which of the following is true for an RTD (Resistance Temperature Detector) compared to a thermistor?

RTDs (typically platinum) have a much more linear relationship between temperature and resistance compared to thermistors.

Daily review: Temperature Sensor | Impedance Analysis | Voltage Divider Rules Quiz