Driver's License Test Prep
California Practice Vehicle Equipment

Fog forces you to turn on your windshield wipers. What headlight rule applies?

  1. A.
    You must switch to high beams and slow down.
  2. B.
    Parking lights alone are enough since visibility is limited.
  3. C.
    You must turn on your low-beam headlights. Correct
The Why

The answer is "You must turn on your low-beam headlights."

Any time you need the wipers for fog, rain, or snow, California requires you to turn on your low-beam headlights. A comes from the reflex of switching to high beams whenever visibility drops, a habit that works on an empty dark road but backfires when the extra light bounces back off airborne droplets.

Why the others miss

The traps in the wrong answers

A. You must switch to high beams and slow down.

High beams reflect off precipitation and reduce visibility; the manual specifies low beams in these conditions. This answer reaches for the brighter setting on the theory that more light always helps in poor weather, without knowing California singles out low beams because high beams bounce back off fog droplets.

B. Parking lights alone are enough since visibility is limited.

Parking lights alone are prohibited for driving at any time; the fog rule calls for low-beam headlights. This answer treats parking lights as an allowable dim setting when visibility is poor, missing that California's ban on driving with them alone has no weather exception.

The Rule

This question tests your knowledge of Vehicle Equipment in California. Source: California Driver Manual, "Using Your Headlights," p.11..

More from this topic

Related California questions

More than a book

You just took one California question apart. The book does it for the whole test.

The California book unlocks a free companion: an adaptive study plan, progress synced across your devices, a denser laminate cheat sheet, and a test-day walkthrough. Verify your copy once, usually in seconds; there's nothing extra to buy.

Get the book on Amazon

$18.99 paperback, free companion included.

Free study plan

Your free California study plan

A short run of study emails for the California DMV test: what to drill, the rules people trip on, and a final pre-test checklist. The printable cheat sheet is free to grab either way.

One email a few times a month. No spam, unsubscribe anytime. Privacy.