When light is refracted into a medium

Options

A. its wavelength and frequency both increase
B. its wavelength increases but frequency remain unchanged
C. its wavelength decreased but frequency remain unchanged
D. its wavelength and frequency both decreased

Explanation

To solve the question regarding the behavior of light when it is refracted into a medium, we will analyze the changes in wavelength and frequency during the refraction process.

### Step-by-Step Solution:

1. **Understanding Refraction**:
Refraction occurs when light passes from one medium to another, causing it to change speed and direction. The two mediums involved are typically a rarer medium (like air or vacuum) and a denser medium (like glass or water).

**Hint**: Remember that light travels at different speeds in different mediums, which affects its wavelength.

2. **Identifying the Mediums**:
In the absence of specific mediums mentioned in the question, we assume the first medium to be vacuum (or air), which is a rarer medium, and the second medium to be a denser medium.

**Hint**: Always consider vacuum as the first medium unless stated otherwise.

3. **Analyzing Wavelength and Frequency**:
- When light enters a denser medium from a rarer medium, its speed decreases.
- The relationship between speed (v), frequency (f), and wavelength (λ) is given by the equation:
\[ v = f \cdot \lambda \]
- Since the frequency of light is determined by the source and does not change during refraction, we conclude that frequency remains unchanged.

**Hint**: Frequency is constant across mediums; it is the speed and wavelength that change.

4. **Determining the Change in Wavelength**:
- As light enters a denser medium, its speed decreases, which means that for the frequency to remain constant, the wavelength must also decrease.
- Therefore, when light is refracted into a denser medium, the wavelength decreases.

**Hint**: Remember that if speed decreases and frequency remains constant, wavelength must decrease.

5. **Conclusion**:
Based on the analysis, when light is refracted into a medium:
- Wavelength decreases.
- Frequency remains unchanged.

Thus, the correct answer is: **Wavelength decreases, frequency remains unchanged**.

### Final Answer:
**C) Wavelength decreases, frequency remains unchanged.**