Between two coherent waves phase is:

Options

A. f(x) = constant
B. (t) = constant
C. f(d) = f(t) = constant
D. f(x) = f(t)

Answer

To solve the question regarding the phase between two coherent waves, we need to understand the concept of coherence and phase difference. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Coherent Waves**:
- Coherent waves are waves that maintain a constant phase difference over time. This means that the waves have the same frequency and their peaks and troughs align consistently.

2. **Defining Phase**:
- The phase of a wave refers to the position of a point in time on a waveform cycle. It is often measured in degrees or radians.

3. **Phase Difference**:
- The phase difference between two waves is determined by the path difference between them. If two waves have a phase difference of \( \Delta \phi \), it can be expressed in terms of the path difference \( \Delta x \) as:
\[ \Delta \phi = \frac{2\pi}{\lambda} \Delta x \]
where \( \lambda \) is the wavelength of the waves.

4. **Condition for Coherence**:
- For two waves to be coherent, the path difference \( \Delta x \) must remain constant. This leads to a constant phase difference \( \Delta \phi \) between the waves.

5. **Conclusion**:
- Therefore, the phase difference between two coherent waves is constant, which means that the path difference \( \Delta x \) is also constant.

### Final Answer:
The phase between two coherent waves is constant.