Refractive index of a medium

Options

A. is dependent of temperature
B. decreases as temperature increases
C. increases as temperature decreases
D. both 'b' and 'c'

Answer

To understand the refractive index of a medium and how it is affected by temperature, we can break down the concept into a step-by-step explanation.

### Step-by-Step Solution:

1. **Definition of Refractive Index**:
The refractive index (n) of a medium is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in that medium (v). Mathematically, it is expressed as:
\[ n = \frac{c}{v} \]

2. **Effect of Temperature on Refractive Index**:
The refractive index of a medium can change with temperature. Generally, as the temperature of a medium increases, its density decreases, which can lead to a decrease in the refractive index. Conversely, when the temperature decreases, the density of the medium increases, which can lead to an increase in the refractive index.

3. **Understanding the Relationship**:
- **Higher Temperature**: When the temperature of a medium increases, the molecules move faster and the medium expands, resulting in a lower density. This typically causes the refractive index to decrease.
- **Lower Temperature**: When the temperature decreases, the molecules slow down, the medium contracts, and the density increases. This usually results in a higher refractive index.

4. **Conclusion**:
Based on the above understanding, we can conclude that the refractive index of a medium is inversely related to temperature. Therefore, if the temperature increases, the refractive index decreases, and if the temperature decreases, the refractive index increases.

### Final Answer:
The refractive index of a medium decreases with an increase in temperature and increases with a decrease in temperature.