An electrical engineer is testing a thermal sensor for an industrial cooling system.
Which of the following descriptions matches the correct circuit symbol for a thermistor?
The engineer calibrates a negative temperature coefficient (NTC) thermistor by cooling it within a temperature-controlled environmental chamber. The resistance of the thermistor is recorded at various temperatures. The table below shows the results:
| Temperature (∘C^{\circ}\text{C}∘C) | Resistance (Ω\OmegaΩ) |
|---|---|
| 20 | 1500 |
| 10 | 2100 |
| 0 | 3000 |
| -20 | 7200 |
| -30 | 11400 |
| -40 | 18000 |
State the independent and dependent variables in this investigation.
Explain which variable should be plotted on the horizontal (xxx) axis and which on the vertical (yyy) axis, including their units.
Describe whether a straight line of best fit or a curve of best fit is more appropriate for these data, and estimate the resistance of the thermistor when the temperature is −10∘C-10^{\circ}\text{C}−10∘C.
Suggest three improvements that could be made to the experimental setup to increase accuracy or reliability.
The thermistor is integrated into a control circuit and connected in series with a 12.0 V direct current supply. At an ambient temperature of 20∘C20^{\circ}\text{C}20∘C, the resistance of the thermistor is 1500 Ω.
State the equation linking voltage, current, and resistance.
Calculate the current in the circuit.
Explain what will happen to the current in the circuit when the temperature of the thermistor increases.
