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Which of the following is a periodic signal?

• sin(t)
• e^t
• t^2
• log(t)
• None of the above

Answer explanation

sin(t) is periodic with period 2π.

The Fourier series is used to represent:

• Aperiodic signals only
• Periodic signals only
• Both periodic and aperiodic signals
• Only real-time signals
• None of the above

Answer explanation

Fourier series can represent both periodic and aperiodic signals using harmonics.

Which system property ensures output depends only on current and past inputs, not future ones?

• Linearity
• Causality
• Time invariance
• Memorylessness
• None of the above

Answer explanation

Causality ensures the system output depends only on current or past inputs.

What is the Laplace transform of a unit step function u(t)?

• 1/s
• s
• 1/(s+1)
• s^2
• None of the above

Answer explanation

Laplace transform of u(t) is 1/s for Re(s) > 0.

In signal processing, convolution is used to determine:

• Signal addition
• Signal multiplication
• System response to input
• Impulse function
• None of the above

Answer explanation

Convolution determines the response of a system to an input signal.