activate input method

[harven]

I am using this code to automatically activate the default input method
when a file is created.

 (add-hook 'find-file-hook
          (lambda () (activate-input-method default-input-method)))

But it does not handle buffers that are not related to a file, e.g. 
buffers created using the switch-to-buffer command.
Is there a way to activate the input method for these newly created buffers ?

Thanks.