Touch screen works with aluminum contact

[Kevsta26]

This is a bit random, but I was using my iPhone and I accidentally tapped the screen of my Apple Watch and it actually opened an app. I gently tested this again (no Apple products were harmed in this test) and I was able to essentially use the aluminum back of my iPhone and iPad as a stylus for my Apple Watch. However, the same doesn't work with aluminum to an iPhone or iPad screen.

Can anyone explain how this works? I'm just curious

 

[oftheheavens]

Not going to lie, I tried it just to see if we were being trolled but your right. how odd... I wonder what the "science" behind it is?

 

[Julien]

Capacitance passing from your hand through the aluminum. The same way the Pencil, stylus and touch gloves work.