I am unclear as to what is permitted on tisha b’av. I see that work is permitted but discouraged.
Is walking okay? Reading novels? Seeing friends? Using electricity?
On Tisha B’av we are in active mourning, and we should not do things that will take our mind, and concentration off the destruction of the Bais Hamikdash. Therefore we don’t go for walks, visit friends, or even read things that will divert our attention for the aveilus. Using electricity is permitted, because what is meant by not doing “melacha” is doing activities that will divert our attention from the aveilus. See the following post https://dinonline.org/2020/07/25/can-one-read-walk-visit-with-friends-on-tisha-bav/