Driver's License Test Prep
Oregon Practice Adverse Conditions

You're driving into thick fog on an Oregon road. Which lights should you use?

  1. A.
    High beams, because they cut through fog better.
  2. B.
    Low beams, because high beams cause glare in fog. Correct
  3. C.
    Hazard lights only.
  4. D.
    Parking lights only, because they reduce glare in fog.
The Why

The answer is "Low beams, because high beams cause glare in fog."

Use low beams in fog, dust, smoke, or any area of low visibility. Light from high beams reflects off the suspended particles in the air, causing glare and making it harder, not easier, to see ahead. Low beams direct light down at the road and reduce backscatter.

Why the others miss

The traps in the wrong answers

A. High beams, because they cut through fog better.

High beams reflect off particles in the air and create glare. Misreading: Inverts the rule; the manual says high-beam light reflects back, causing glare and making it more difficult to see ahead.

C. Hazard lights only.

Hazard lights are not headlights; you still need low-beam headlights for visibility. Misreading: Substitutes hazard lights for headlights; the manual specifies low-beam headlights in low visibility.

D. Parking lights only, because they reduce glare in fog.

It is illegal to drive at night or in bad weather with only parking lights on; you need low-beam headlights. Misreading: Confuses parking lights with headlights; the manual states it is illegal to drive at night or in bad weather with only the parking lights on.

The Rule

This question tests your knowledge of Adverse Conditions in Oregon. Source: Oregon Driver Manual, "Fog, Dust and Smoke," p.77..

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