A light bulb goes off

[masterding]

Quote from 《iGenius: How Steve Jobs Changed the World 》
A light bulb goes off. And he says, wow, I can put computers on every desktop.
I guess "A light bulb goes off" means when someone suddenly realizes sth. In this sense ,why not say "A light bulb goes on" instead of "goes off"?
Thanks.

 

[SlickVic9000]

(Not a Teacher)

The lightbulb is "going off" in the sense of an alarm or buzzer going off. I'm not sure how else to describe it.

 

[SoothingDave]

This is the classic symbol of an idea coming to someone - that a light bulb turns on.

In English, unfortunately, we often say that things that happen suddenly "go off." Like I lit a firecracker and it almost went off in my hand. Or, I was having a nice dream when my alarm clock went off.

Yes. In English, something like an alarm clock can "go off" when it turns on.

 

[Barb_D]

Somewhere there are a few threads about how illogical it is to say "an alarm went off" to mean it made a noise.

It's logical to think that an alarm goes ON to mean it makes a noise and it goes OFF when it's silenced, but no... we say "My alarm didn't go off" to mean it never sounded or "I have to get off the phone -- the fire alarm just went off."

English is often not very logical.

 

[5jj]

English is often not very logical.

Thank goodness. I would have had to work for a living if it had been.;-)

 

[Barb_D]

And I'd have to work harder if most people used it well. ;-)

 

[SoothingDave]

A house can burn up as it burns down.

 

[masterding]

What if I replace "off" with "on", and say" A light bulb goes on. And he says, wow, I can put computers on every desktop." Does it make sense? or does it have any different meaning?

 

[SoothingDave]

Same meaning.

 

[masterding]

Same meaning.

English is such an amazing language! On and off can have the same meaning, So can up and down, and maybe so can in and out and so on.

 

[5jj]

This is one of the many reasons we keep saying in this forum that context is so important,

 

[emsr2d2]

I have always assumed that "to go off" for alarm clocks etc was used in the same way that it means "to explode".

A firework goes off. A bomb goes off. A flashgun (on a camera) goes off.

Fair enough, I can't explain why we use that particular phrasal verb to mean "to explode" but that's the use of it that I imagine when I hear that an alarm clock has "gone off" - usually it wakes you up with such a fright that it may as well have been a bomb!