Is it possible to use a cloned operating system through an external disk connected by USB?

I'm trying to clone a laptop's disk using an external hard drive in order to then use it on a different computer. The problem is that while the external HDD has enough space (1TB), the other computer doesn't. Hence the question -- is it possible to clone the entire disk (dual boot with Ubuntu and Windows) to the external 1TB hard drive, and then boot and use the OS directly from the external disk plugged in by USB, and if so, is it a good idea?

Question by Case on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.