how to test christmas light bulbs

You can test Christmas light bulbs by following these steps: 1. Unplug the lights from the outlet. 2. Remove one of the bulbs from the strand and gently twist it out of its socket. 3. Check the bulb's filament for any visible signs of damage or discoloration. 4. Touch the bulb's contacts to a 9-volt battery. If the bulb lights up, it is working properly. If not, replace it with a new one. 5. Reattach the bulb to the socket and plug the strand back in. The light should now be working properly.