Question Headlights are required when visibility is less than: Answers 100 feet. 300 feet. 500 feet. Explanation Iowa law requires drivers to use their headlights from sunset to sunrise. Headlights must also be used at any other time when visibility is limited to 500 feet or less. Pass your DMV Written Test with flying colors Take me to the cheat sheet Iowa This questions appears in the following tests: Iowa Practice Test 22 Iowa Practice Test 7