Final answer:
Bright beams should be used for driving at night to improve visibility, but they should not be used in foggy conditions or during heavy rain due to increased scattering of light that can reduce visibility.
Step-by-step explanation:
Bright beams should be used for driving at night when visibility is low due to lack of ambient light and to illuminate the road far ahead. However, using bright beams in foggy conditions or heavy rain can be counterproductive. When light from headlights is scattered by particles such as water droplets or fog, it diffuses and creates a glare, which can actually decrease visibility for the driver. Instead, low beams or fog lights, which are designed to have a lower and wider pattern of light, are recommended for these weather conditions to reduce glare and improve visibility close to the vehicle.
Headlights like those in searchlight beams or car headlights use mirrors to trap most of the bulb's light and form a directional beam, as demonstrated in the figures provided. The directional nature of headlights is crucial for effective illumination of the road while minimizing the scattering of light, which can lead to reduced visibility.