The thermistors are usually made of

Options

A. metal with low temperature coefficient of resistivity
B. metals with high temperature coefficient of resistivity
C. metal oxides with high temperature coefficient of resistivity
D. semiconducting materials having low temperature coefficient of resistivity

Answer

To determine what thermistors are usually made of, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Thermistors**:
- A thermistor is a type of resistor whose resistance varies significantly with temperature. The term "thermistor" itself indicates that it is related to temperature (therm-).

2. **Identifying Materials**:
- Thermistors are typically made from materials that have a high temperature coefficient of resistivity. This means that the resistance of the material changes rapidly with temperature changes.

3. **Types of Materials**:
- The common materials used for thermistors include:
- Metal oxides
- Semiconductors
- Among these, metal oxides are the most commonly used due to their favorable properties for temperature sensing.

4. **High Temperature Coefficient**:
- The high temperature coefficient of resistivity is crucial for thermistors because it allows for a significant change in resistance with small changes in temperature. This sensitivity is what makes thermistors useful in temperature measurement and control.

5. **Conclusion**:
- Based on the above points, we conclude that thermistors are usually made of metal oxides, which have a high temperature coefficient of resistivity.

### Final Answer:
Thermistors are usually made of **metal oxides**.

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