This question was asked inGPSC AE (Electrical) Class-2 R&B Department Paper 2025 – Series MQuestion 68 of 179 published · Gujarat Public Service CommissionOpen paper
Q178EasySignals & Classification

When is x(t) said to be non-periodic signal?

Answer & step-by-step solution
Correct answer: C. If the equation x (t) = x (t + T) is satisfied for no values of T
Quick explanation

A continuous-time signal is periodic only if there exists at least one finite positive T such that x(t+T)=x(t) for all t. If no positive finite T satisfies that condition, the signal is non-periodic (aperiodic).

∃ T₀ > 0 such that x(t+T₀)=x(t) ∀t

Concept & Reasoning

The period condition must hold for every time t, but only one positive fundamental period needs to exist; integer multiples of it are also periods. Therefore the phrase 'no values of T' should be interpreted as no non-zero finite positive period.

How to Solve It in the Exam

Existence of one positive period is enough.

Important Exam Point

Do not mistake 'for all t' (time variable) with 'for all T' (candidate period).

Quick Trick

Existence of one positive period is enough.

Common Mistake

Saying a periodic signal must satisfy the equation for every possible T.

Solution diagram – When is x(t) said to be non-periodic signal?
Exam tipDo not mistake 'for all t' (time variable) with 'for all T' (candidate period).
Verified · SRO editorial desk Report
Try it before reading the solution — tap an option.0/1✓ 0✗ 0

More Signals & Classification questions