In a inser tube all the photons

Options

A. have same wavelength
B. have same energy
C. move in same direction
D. move with same speed

Answer

To solve the question regarding the characteristics of photons in a laser tube, we need to analyze the properties of the photons emitted by a laser.

### Step-by-Step Solution:

1. **Understanding Photon Properties**:
- Photons are particles of light that have specific properties such as wavelength, energy, direction, and speed.

2. **Same Wavelength**:
- In a laser tube, all photons typically have the same wavelength. This is a characteristic of laser light, which is monochromatic.

3. **Same Energy**:
- The energy of a photon is given by the formula \( E = \frac{hc}{\lambda} \), where \( h \) is Planck's constant, \( c \) is the speed of light, and \( \lambda \) is the wavelength. Since all photons in a laser have the same wavelength, they also have the same energy.

4. **Direction of Travel**:
- While laser light is highly directional, it is not completely free from divergence. Therefore, not all photons travel in exactly the same direction, though they are mostly parallel.

5. **Speed of Photons**:
- In a vacuum, all photons travel at the speed of light, \( c \), which is approximately \( 3 \times 10^8 \) meters per second. This is true for all photons regardless of their energy or wavelength.

6. **Conclusion**:
- Based on the analysis, the correct statement about the photons in a laser tube is that they "move with the same speed." This is true since all photons travel at the speed of light in a vacuum.

### Final Answer:
The correct option is: **D. Move with the same speed.**

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