Use of chi

We've been playing with chi for the past few weeks.
I've a new crop of black belts so now's the time.
Here's a good one for you to try.
Concentrate on the first 2 fingers of your favourite striking hand.
Using just these two fingers snap a very quick snap on your training partners bare arm saying "Cha" (very softly).
Time the words to the snap.
We got some blisters coming up like when we do Red Sand Palm, so I turned the lights out and when it really works you get sparks!!!!

i`d like to learn more tai chi as it looks good and seems so relaxed

I've just self edited my views on Tai Chi,what is it?
It's not a martial art, it's not meditation, it's not chi gung personally I'm underwhelmed with it.
What use is it? A bunch of old gummers moving in slow motion.
It's like aikido, looks pretty but if if try to bite your face off will it stop me?