Wonderful old military videos showing explanation of the DC generator vs the AC version. The DC generator output is called pulsating DC. This is because it still has minimum and peak voltage proportional to the position of the coil to the magnet throughout the 360 degrees of rotation.
You can find so many nice videos for DC and AC machines in youtube. These principles are the foundations for all of electrical current and motion… great fun to experiment with!
Part 1, 1961 34 minutes… Part 2 below it. I first watched these videos in the 1970s while doing my airforce electronics training. 16mm film back then on a Bell & Howell projector!