Which distance is appropriate for dimming headlights in fog?

• A. 200 feet
• B. 1000 feet
• C. 500 feet
• D. 300 feet

Answer: (C)

Fog makes headlights reflect off water droplets, creating glare that can wash out your vision. Using low beams keeps light aimed at the road and reduces that backscatter, helping you see with less glare for others.

The standard guideline is to dim to low beams when you’re within about 500 feet of another vehicle. That distance balances getting enough light to spot hazards while avoiding blinding oncoming drivers or following vehicles. If you wait until 1000 feet, glare from the fog and oncoming traffic can still be a problem; if you dim much earlier, like 200 or 300 feet, you reduce your own visibility more than necessary. So 500 feet is the appropriate threshold.