Final Answer:
Lower headlight beams must be used when approaching within 500 feet of an oncoming vehicle or when following 300 feet of the rear of another vehicle.
Step-by-step explanation:
1. **Approaching Within 500 Feet:**
- Paraphrasing the question, lower headlight beams are required when getting close to an oncoming vehicle. This is crucial for preventing glare and ensuring safety. Approaching within 500 feet necessitates adjusting the headlights to avoid blinding the driver of the oncoming vehicle.
- When a vehicle is within 500 feet, it's essential to minimize the intensity of the headlights to maintain visibility without causing discomfort or danger to the other driver.
2. **Following Within 300 Feet:**
- Lower headlight beams are also mandated when following within 300 feet of the rear of another vehicle. This distance is a safety measure to prevent dazzling the driver in front, which could lead to accidents or discomfort.
- The 300-feet rule recognizes that proximity matters; maintaining lower headlight beams in such situations ensures that the driver ahead is not adversely affected by the headlights.
In summary, lower headlight beams are required within 500 feet of an oncoming vehicle and within 300 feet when following another vehicle. These rules prioritize safety, visibility, and considerate driving practices, minimizing the risk of accidents and promoting a safer driving environment.