In other words, if one bulb goes, all of them can go dark.

"It was as if a light bulb went off in my head."

We looked at each other and the light bulb went off.

Those bulbs go all the time, I'd say, and one more isn't going to put the place on red alert.

A light bulb went off the first day of rehearsal.

But then the light bulb went on over somebody's head.

A light bulb went off in both their minds at about the same time.

There should have been a yellow one too but the bulb had gone.

Ryan could almost see the light bulb go on over his head.

It was sort of like a light bulb went off.