Why cathode ray tube experiment is not conducted at atmospheric pressure?

Answer

**Step-by-Step Solution:**

1. **Understanding the Cathode Ray Tube (CRT):**
- A cathode ray tube is a vacuum tube that contains two electrodes: a cathode (negative electrode) and an anode (positive electrode). When a high voltage is applied, electrons are emitted from the cathode and travel towards the anode, creating cathode rays.

2. **Role of Vacuum in CRT:**
- The cathode ray tube is designed to operate in a vacuum. This means that the air pressure inside the tube is significantly lower than atmospheric pressure. The vacuum is crucial for the proper functioning of the CRT.

3. **Effect of Atmospheric Pressure:**
- If the cathode ray tube were to be operated at atmospheric pressure, the air molecules present inside the tube would collide with the emitted electrons (cathode rays). These collisions would impede the movement of the electrons.

4. **Consequences of Collisions:**
- Due to the numerous collisions with air molecules, the distance traveled by the cathode rays would be drastically reduced. The electrons would lose energy and scatter, making it impossible for them to travel effectively from the cathode to the anode.

5. **Conclusion:**
- Therefore, conducting the cathode ray tube experiment at atmospheric pressure is not feasible because the cathode rays would not be able to travel freely and would not produce the desired effects, such as the formation of images or patterns on a screen.

**Final Answer:**
The cathode ray tube experiment is not conducted at atmospheric pressure because the presence of air molecules would cause numerous collisions with the emitted cathode rays, significantly reducing their travel distance and preventing the experiment from yielding meaningful results.

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