Which device's resistance decreases as temperature increases?

Which device's resistance decreases as temperature increases?

• A. Diode
• B. Thermistor
• C. LDR
• D. Wires

Answer: (B)

Resistance changing with temperature is being tested. A thermistor is a resistor whose value changes with temperature, and for most thermistors the resistance falls as temperature rises. This is because the semiconductor material in an NTC thermistor has more charge carriers at higher temperatures, making it easier for current to flow. So, as temperature increases, the thermistor’s resistance decreases, which matches the described behavior. Other options don’t fit this specific temperature-driven resistance change: a diode is a non-linear junction whose current–voltage behavior isn’t simply described by a resistance that decreases with temperature; an LDR changes mainly with light, not temperature; and wires actually have higher resistance when they’re hotter because the metal’s resistivity increases with temperature.

Resistance changing with temperature is being tested. A thermistor is a resistor whose value changes with temperature, and for most thermistors the resistance falls as temperature rises. This is because the semiconductor material in an NTC thermistor has more charge carriers at higher temperatures, making it easier for current to flow.

So, as temperature increases, the thermistor’s resistance decreases, which matches the described behavior.

Other options don’t fit this specific temperature-driven resistance change: a diode is a non-linear junction whose current–voltage behavior isn’t simply described by a resistance that decreases with temperature; an LDR changes mainly with light, not temperature; and wires actually have higher resistance when they’re hotter because the metal’s resistivity increases with temperature.