According to Ohio law, what must you do when using your windshield wipers?

In Ohio, when you use your windshield wipers, it is required by law to switch on your headlights. This rule is in place to ensure that your vehicle is visible to other drivers, especially in conditions of reduced visibility such as rain, fog, or snowy weather. The headlights help to enhance your visibility on the road and allow other motorists to see you more clearly. This safety measure is crucial to prevent accidents during such weather conditions.

The other options do not directly pertain to safety regulations regarding the use of windshield wipers. Using high beams in adverse weather conditions can actually reduce visibility, as they may reflect off rain or snow. Activating turn signals is unrelated to the operation of windshield wipers. Opening windows for ventilation does not contribute to visibility or safety while driving in poor weather conditions. Thus, switching on your headlights is the appropriate action to take when utilizing your windshield wipers in Ohio.