Question

What is the time period of a periodic signal in actual terms?

(a) The signals which start at t=-∞ and end at t=+∞

(b) The signals which have a finite interval of occurrence

(c) The signals which start at t= -∞ and ends at a finite time period

(d) The signals which have a short period of occurrence

I had been asked this question in unit test.

My question is from Periodic Signals topic in chapter Fourier Series of Signals and Systems

Answer 1

Right option is (a) The signals which start at t=-∞ and end at t=+∞

Explanation: The periodic signals have actually a time period between t=-∞ and at t= + ∞. These signals have an infinite time period, that is periodic signals are actually continued forever. But this is not possible in case of real time signals.