Question

What are periodic signals?

(a) The signals which change with time

(b) The signals which change with frequency

(c) The signal that repeats itself in time

(d) The signals that repeat itself over a fixed frequency

I got this question during an internship interview.

The doubt is from Periodic Signals in portion Fourier Series of Signals and Systems

Answer 1

The correct answer is (c) The signal that repeats itself in time

The explanation is: Those signals which repeat themselves in a fixed interval of time are called periodic signals. The continuous-time signal x(t) is periodic if and only if

x(t+T)= x(t).