The design of the Mac Magsafe 1 power adapter means that if someone walks past your MacBook Pro while it is plugged into the mains power and kicks your Magsafe 1 mains adapter cable then because it is only connected via a magnetic link it will simply disconnect from your MacBook Air.
This will therefore minimize undue strain on both the Magsafe 1 power port and MacBook Air power cable
This Apple compatible 45W mains adapter will charge your MacBook Air battery while turned on, turned off or in sleep mode. If you have no battery fitted, then it will simply power your MacBook Air.
Connector: Magsafe 1 (Magnetic 5 Pin)
input: 100-240V ~ 1.0 and 50-60Hz
output: 14.5 in --- 3.1 connecting
adapters: 1 x 5 PIN magnetic connector model
Type: A1244ADP-45gd B
Compatibility: MacBook Air