I've been studying harmonics at school for a while. Speaking of them I discovered that a particular case of harmonic is that of a square wave. I know that this wave is composed of a fundamental and only odd harmonics, this if the square wave has a duty cycle of 50%. I didn't understand what "this" duty cycle is. Could anyone be able to explain it to me briefly and broadly?
Technically, a square wave is a special case of a pulse wave with a duty cycle of 50%, but sometimes pulse waves with other duty cycles are called square waves too.
A square wave signal spends 50% of the period high and 50% of the period low, so it has a duty cycle of 50%.
Pulse wave with 10% duty cycle spends 10% of the period high and 90% of the period low.