Not sure if this is the right Stack Exchange for this question, but please point me toward a better site if it exists.
In Daniel Dennett's book, "Consciousness Explained," he writes:
Standard motion pictures run at twenty-four frames per second, so the film advances a frame every 42msec (actually, each frame is held stationary and exposed three times during that 42msec, for durations of 8.5msec, with 5.4msec of darkness between each). 
Is this still true for digital cinema projectors? (The book is from 2017, but I'm still not sure what he means by "standard" motion pictures.) From what I can tell on Wikipedia, digital cinema still uses the concept of "frame rate," but the notion may not be as clear-cut as it was for traditional film.
An additional question is: Where can I find information on the exact bright/dark timing used for different frame rates, video standards, and technologies? I find it fascinating that the screen could be dark 40% of the duration of a movie without the viewer realizing it, and would love to be able to look up this kind of fact for TV and other media.
 Dennett, Daniel C. Consciousness Explained (p. 103). Little, Brown and Company.