When light travels from one medium to the other of which the refractive index is different, then which of the following will change

Options

A. Frequency, wavelength and velocity
B. Frequency and wavelength
C. Frequency and velocity
D. Wavelength and velocity

Answer

To solve the question regarding what changes when light travels from one medium to another with different refractive indices, we can analyze the properties of light and the behavior of waves at the interface of two different media.

### Step-by-Step Solution:

1. **Understanding Refractive Index**:
The refractive index (µ) of a medium is defined as the ratio of the speed of light in vacuum (c) to the speed of light in that medium (v). This can be expressed as:
\[ \mu = \frac{c}{v} \]
where \(c\) is the speed of light in vacuum and \(v\) is the speed of light in the medium.

2. **Change in Velocity**:
When light enters a medium with a different refractive index, its speed changes. If the refractive index increases (light moving from a less dense to a denser medium), the speed of light decreases. Conversely, if the refractive index decreases (light moving from a denser to a less dense medium), the speed of light increases. Therefore, the velocity of light changes when it moves from one medium to another.

3. **Frequency of Light**:
The frequency of light is determined by the source of the light and remains constant when light transitions between different media. This is because frequency is related to the energy of the photons, which does not change when light enters a new medium.

4. **Wavelength of Light**:
The relationship between speed (v), frequency (f), and wavelength (λ) of light is given by the equation:
\[ v = f \cdot \lambda \]
Since the frequency (f) remains constant and the velocity (v) changes when light enters a new medium, the wavelength (λ) must also change to satisfy this equation. Specifically, if the speed of light decreases, the wavelength decreases, and if the speed increases, the wavelength increases.

5. **Conclusion**:
From the analysis, we conclude that when light travels from one medium to another with different refractive indices:
- The **velocity** of light changes.
- The **wavelength** of light changes.
- The **frequency** of light remains constant.

Thus, the correct answer is that the **wavelength and velocity change**.

### Final Answer:
The correct option is **D: Wavelength and Velocity**.