Question

What is resistivity class 10 NCERT?

Answer 1

In Class 10 NCERT physics, **resistivity** is a fundamental concept related to electrical resistance. Here’s a detailed explanation:

### **Resistivity (ρ)**

**Definition:**
Resistivity is a property of a material that quantifies how strongly it resists the flow of electric current. It is defined as the resistance of a unit length of the material with a unit cross-sectional area.

**Formula:**
The resistivity \( \rho \) of a material is given by:

\[ \rho = R \times \frac{A}{L} \]

where:
- \( R \) = Resistance of the material (in ohms, Ω)
- \( A \) = Cross-sectional area of the material (in square meters, m²)
- \( L \) = Length of the material (in meters, m)

**Units:**
The unit of resistivity in the International System of Units (SI) is ohm-meter (Ω·m).

**Characteristics:**
1. **Material Dependence:** Resistivity is intrinsic to the material, meaning it depends only on the type of material and its temperature, but not on its shape or size.
2. **Temperature Dependence:** Resistivity generally increases with temperature for conductors (like metals) and decreases with temperature for insulators (like semiconductors).
3. **Nature of Material:** Different materials have different resistivities. For instance, metals have low resistivity, making them good conductors, while insulators have high resistivity.

**Practical Examples:**
- **Conductors** (e.g., copper, aluminum) have low resistivity and are used in electrical wiring.
- **Insulators** (e.g., rubber, glass) have high resistivity and are used to coat wires and prevent leakage of current.

**Applications:**
Understanding resistivity helps in choosing the right material for specific electrical applications, designing electrical components, and improving energy efficiency in electrical systems.

In the NCERT curriculum, this concept is fundamental for understanding how electrical circuits function and how different materials impact electrical resistance.

Answer 2

Resistivity, often referred to as **specific resistance**, is a property of a material that defines how strongly it resists the flow of electric current. According to **Class 10 NCERT**, resistivity is a fundamental concept in the chapter on **Electricity**.

### Definition:
Resistivity of a material is defined as the resistance offered by a wire of that material having a unit length and unit cross-sectional area. It is denoted by the Greek letter **ρ (rho)** and is expressed mathematically as:

\[
ρ = R \cdot \frac{A}{L}
\]

where:
- \(R\) is the resistance of the conductor,
- \(A\) is the cross-sectional area of the conductor,
- \(L\) is the length of the conductor.

### Key Points:
- **Resistivity depends on the material** of the conductor, not its dimensions. Different materials have different resistivities.
  - Conductors (like copper, aluminum) have **low resistivity**.
  - Insulators (like rubber, glass) have **high resistivity**.
- **SI Unit**: The SI unit of resistivity is **ohm meter (Ω·m)**.
- **Temperature dependence**: Resistivity typically increases with temperature for conductors and decreases with temperature for some insulators.

### Importance:
In practical applications, resistivity helps determine which materials are good conductors or insulators, essential for designing electrical circuits and devices.

In summary, resistivity is a material property that influences how easily or difficultly electric current flows through a substance, based on its inherent characteristics.