Power Supply Amperage for External USB Disk Drive

[infocorp9]

What amperage range is acceptable for an external usb hard drive?

I have three 12 volt power supplies with 1.2amp, 4.0amp and 5.0amp.

Are any of them suitable for an external usb hard disk drive?

 

[jsc]

The larger WD externals ship with a power adapter that provides 1.5 amp at 12 volts.

The 1.2 amp PS might work.