set off the metal detector

[keannu]

Does it mean "You are caught while going through the metal detector due to metals in your body"? "Set off" doesn't seem to make that kind of meaning, so I'm curious. This is from a workbook explaining airport stuff.

ex)He set off the metal detector at the airport.
gibon140

 

[Barb_D]

I could be for any reason. A metal pin in his ankle after surgery. A wrist watch he forgot to take off. A money clip in his pocket. The metal detector went "off" (alerted, beeped, whatever it does).

 

[BobK]

Does it mean "You are caught while going through the metal detector due to metals in your body"? "Set off" doesn't seem to make that kind of meaning, so I'm curious. This is from a workbook explaining airport stuff.

ex)He set off the metal detector at the airport.
gibon140

:-? 'Set off' is often used like this. 'The burglar stepped on the pressure-pad and set off an alarm'. If you wanted one word, it would be something like 'trigger' (v.)

b