Can a 2015 Macbook Air MagSafe 2 connector be filed down to work with a 2009 Macbook Pro? The title pretty much says it all. I ordered a MagSafe 2 power adapter before realizing my MacBook Pro uses the Original MagSafe. After looking at both connectors, it appears the MagSafe 2 connector would fit the MagSafe power port if it were filed down on the edges a bit. However, I'm concerned the power delivery would not match what the computer can handle, and I don't really want to go through returning and buying a new power adapter. Likewise, I wouldn't want to destroy both the adapter and the computer at one go. Does anyone know the specs – whether these two are "electrically compatible?"
I'm pretty much sure there is some difference between MagSafe and MagSafe2 plugs.  Another page for overview is right power adapter and cord
from Apple. 
On other hand Apple has made it clear that an adapter with the same or higher wattage than originally provided may be used without problems. So should you have a chance to apply your MagSafe2 plug for your MagSafe notebook - imho that would work