If using two channels on an oscilloscope, does the ground clip of each probe need to be connected?

Question

I'm not talking about isolated scopes. For a normal oscilloscope, would connecting ONE ground clip be sufficient?

Answer 1

The proper method would be to connect both ground clips, but it is important that both go to the same point in the circuitry, so that you don't accidentally create a ground loop.

Answer 2

At low frequencies it makes little difference if you use only one earth. However, at high frequencies and pulse repetition rates ( with fast rise times) you will get considerable ringing unless you use both.