When a substance conducts elecricity without any resistance, it is called a …….. .

Answer

To solve the question, "When a substance conducts electricity without any resistance, it is called a ……..", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Substances**:
- There are three main types of substances based on their electrical conductivity: conductors, insulators, and semiconductors.
- Conductors allow the flow of electricity but with some resistance.
- Insulators do not allow electricity to flow easily and have high resistance.
- Semiconductors have properties between conductors and insulators and can conduct electricity under certain conditions.

2. **Identify the Key Term**:
- The question specifically asks for a substance that conducts electricity without any resistance. This means we are looking for a special category of conductors.

3. **Define the Special Category**:
- The substance that conducts electricity without any resistance is known as a "superconductor." Superconductors exhibit zero electrical resistance and expel magnetic fields when cooled below a certain critical temperature.

4. **Conclusion**:
- Therefore, the answer to the question is: "superconductor."

### Final Answer:
When a substance conducts electricity without any resistance, it is called a **superconductor**.

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